# The Netwide Assembler: NASM

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## Appendix C: NASM Version History

### C.1 NASM 2 Series

The NASM 2 series support x86-64, and is the production version of NASM since 2007.

#### C.1.1 Version 2.10.01

- Add missing VPMOVMSKB instruction with reg32, ymmreg operands.

#### C.1.2 Version 2.10

- When optimization is enabled, `mov r64,imm` now optimizes to the shortest form possible between:

         mov r32,imm32                   ;  5 bytes
         mov r64,imm32                   ;  7 bytes
         mov r64,imm64                   ; 10 bytes

To force a specific form, use the `STRICT` keyword, see section 3.7.

- Add support for the Intel AVX2 instruction set.
- Add support for Bit Manipulation Instructions 1 and 2.
- Add support for Intel Transactional Synchronization Extensions (TSX).
- Add support for x32 ELF (32-bit ELF with the CPU in 64-bit mode.) See section 7.9.
- Add support for bigendian UTF-16 and UTF-32. See section 3.4.5.

#### C.1.3 Version 2.09.10

- Fix up NSIS script to protect uninstaller against registry keys absence or corruption. It brings in a few additional questions to a user during deinstallation procedure but still it is better than unpredictable file removal.

#### C.1.4 Version 2.09.09

- Fix initialization of section attributes of `bin` output format.
- Fix `mach64` output format bug that crashes NASM due to NULL symbols.

#### C.1.5 Version 2.09.08

- Fix `__OUTPUT_FORMAT__` assignment when output driver alias is used. For example when `-f elf` is used `__OUTPUT_FORMAT__` must be set to `elf`, if `-f elf32` is used `__OUTPUT_FORMAT__` must be assigned accordingly, i.e. to `elf32`. The rule applies to all output driver aliases. See section 4.12.6.

#### C.1.6 Version 2.09.07

- Fix attempts to close same file several times when `-a` option is used.
- Fixes for VEXTRACTF128, VMASKMOVPS encoding.

#### C.1.7 Version 2.09.06

- Fix missed section attribute initialization in `bin` output target.

#### C.1.8 Version 2.09.05

- Fix arguments encoding for VPEXTRW instruction.
- Remove invalid form of VPEXTRW instruction.
- Add `VLDDQU` as alias for `VLDQQU` to match specification.

#### C.1.9 Version 2.09.04

- Fix incorrect labels offset for VEX intructions.
- Eliminate bogus warning on implicit operand size override.
- `%if` term could not handle 64 bit numbers.
- The COFF backend was limiting relocations number to 16 bits even if in real there were a way more relocations.

#### C.1.10 Version 2.09.03

- Print `%macro` name inside `%rep` blocks on error.
- Fix preprocessor expansion behaviour. It happened sometime too early and sometime simply wrong. Move behaviour back to the origins (down to NASM 2.05.01).
- Fix unitialized data dereference on OMF output format.
- Issue warning on unterminated `%{` construct.
- Fix for documentation typo.

#### C.1.11 Version 2.09.02

- Fix reversed tokens when `%deftok` produces more than one output token.
- Fix segmentation fault on disassembling some VEX instructions.
- Missing `%endif` did not always cause error.
- Fix typo in documentation.
- Compound context local preprocessor single line macro identifiers were not expanded early enough and as result lead to unresolved symbols.

#### C.1.12 Version 2.09.01

- Fix NULL dereference on missed %deftok second parameter.
- Fix NULL dereference on invalid %substr parameters.

#### C.1.13 Version 2.09

- Fixed assignment the magnitude of `%rep` counter. It is limited to 62 bits now.
- Fixed NULL dereference if argument of `%strlen` resolves to whitespace. For example if nonexistent macro parameter is used.
- `%ifenv`, `%elifenv`, `%ifnenv`, and `%elifnenv` directives introduced. See section 4.4.9.
- Fixed NULL dereference if environment variable is missed.
- Updates of new AVX v7 Intel instructions.
- `PUSH imm32` is now officially documented.
- Fix for encoding the LFS, LGS and LSS in 64-bit mode.
- Fixes for compatibility with OpenWatcom compiler and DOS 8.3 file format limitation.
- Macros parameters range expansion introduced. See section 4.3.4.
- Backward compatibility on expanging of local sigle macros restored.
- 8 bit relocations for `elf` and `bin` output formats are introduced.
- Short intersegment jumps are permitted now.
- An alignment more than 64 bytes are allowed for `win32`, `win64` output formats.
- `SECTALIGN` directive introduced. See section 4.12.13.
- `nojmp` option introduced in `smartalign` package. See section 5.2.
- Short aliases `win`, `elf` and `macho` for output formats are introduced. Each stands for `win32`, `elf32` and `macho32` accordingly.
- Faster handling of missing directives implemented.
- Various small improvements in documentation.
- No hang anymore if unable to open malloc.log file.
- The environments without vsnprintf function are able to build nasm again.
- AMD LWP instructions updated.
- Tighten EA checks. We warn a user if there overflow in EA addressing.
- Make `-Ox` the default optimization level. For the legacy behavior, specify `-O0` explicitly. See section 2.1.22.
- Environment variables read with `%!` or tested with `%ifenv` can now contain non-identifier characters if surrounded by quotes. See section 4.10.2.
- Add a new standard macro package `%use fp` for floating-point convenience macros. See section 5.3.

#### C.1.14 Version 2.08.02

- Fix crash under certain circumstances when using the `%+` operator.

#### C.1.15 Version 2.08.01

- Fix the `%use` statement, which was broken in 2.08.

#### C.1.16 Version 2.08

- A number of enhancements/fixes in macros area.
- Support for converting strings to tokens. See section 4.1.9.
- Fuzzy operand size logic introduced.
- Fix COFF stack overrun on too long export identifiers.
- Fix Macho-O alignment bug.
- Fix crashes with -fwin32 on file with many exports.
- Fix stack overrun for too long [DEBUG id].
- Fix incorrect sbyte usage in IMUL (hit only if optimization flag passed).
- Append ending token for `.stabs` records in the ELF output format.
- New NSIS script which uses ModernUI and MultiUser approach.
- Visual Studio 2008 NASM integration (rules file).
- Warn a user if a constant is too long (and as result will be stripped).
- The obsoleted pre-XOP AMD SSE5 instruction set which was never actualized was removed.
- Fix stack overrun on too long error file name passed from the command line.
- Bind symbols to the .text section by default (ie in case if SECTION directive was omitted) in the ELF output format.
- Fix sync points array index wrapping.
- A few fixes for FMA4 and XOP instruction templates.
- Add AMD Lightweight Profiling (LWP) instructions.
- Fix the offset for `%arg` in 64-bit mode.
- An undefined local macro (`%$`) no longer matches a global macro with the same name.
- Fix NULL dereference on too long local labels.

#### C.1.17 Version 2.07

- NASM is now under the 2-clause BSD license. See section 1.1.2.
- Fix the section type for the `.strtab` section in the `elf64` output format.
- Fix the handling of `COMMON` directives in the `obj` output format.
- New `ith` and `srec` output formats; these are variants of the `bin` output format which output Intel hex and Motorola S-records, respectively. See section 7.2 and section 7.3.
- `rdf2ihx` replaced with an enhanced `rdf2bin`, which can output binary, COM, Intel hex or Motorola S-records.
- The Windows installer now puts the NASM directory first in the `PATH` of the "NASM Shell".
- Revert the early expansion behavior of `%+` to pre-2.06 behavior: `%+` is only expanded late.
- Yet another Mach-O alignment fix.
- Don't delete the list file on errors. Also, include error and warning information in the list file.
- Support for 64-bit Mach-O output, see section 7.8.
- Fix assert failure on certain operations that involve strings with high-bit bytes.

#### C.1.18 Version 2.06

- This release is dedicated to the memory of Charles A. Crayne, long time NASM developer as well as moderator of `comp.lang.asm.x86` and author of the book Serious Assembler. We miss you, Chuck.
- Support for indirect macro expansion (`%[...]`). See section 4.1.3.
- `%pop` can now take an argument, see section 4.7.1.
- The argument to `%use` is no longer macro-expanded. Use `%[...]` if macro expansion is desired.
- Support for thread-local storage in ELF32 and ELF64. See section 7.9.4.
- Fix crash on `%ifmacro` without an argument.
- Correct the arguments to the `POPCNT` instruction.
- Fix section alignment in the Mach-O format.
- Update AVX support to version 5 of the Intel specification.
- Fix the handling of accesses to context-local macros from higher levels in the context stack.
- Treat `WAIT` as a prefix rather than as an instruction, thereby allowing constructs like `O16 FSAVE` to work correctly.
- Support for structures with a non-zero base offset. See section 4.12.10.
- Correctly handle preprocessor token concatenation (see section 4.3.9) involving floating-point numbers.
- The `PINSR` series of instructions have been corrected and rationalized.
- Removed AMD SSE5, replaced with the new XOP/FMA4/CVT16 (rev 3.03) spec.
- The ELF backends no longer automatically generate a `.comment` section.
- Add additional "well-known" ELF sections with default attributes. See section 7.9.2.

#### C.1.19 Version 2.05.01

- Fix the `-w`/`-W` option parsing, which was broken in NASM 2.05.

#### C.1.20 Version 2.05

- Fix redundant REX.W prefix on `JMP reg64`.
- Make the behaviour of `-O0` match NASM 0.98 legacy behavior. See section 2.1.22.
- `-w-user` can be used to suppress the output of `%warning` directives. See section 2.1.24.
- Fix bug where `ALIGN` would issue a full alignment datum instead of zero bytes.
- Fix offsets in list files.
- Fix `%include` inside multi-line macros or loops.
- Fix error where NASM would generate a spurious warning on valid optimizations of immediate values.
- Fix arguments to a number of the `CVT` SSE instructions.
- Fix RIP-relative offsets when the instruction carries an immediate.
- Massive overhaul of the ELF64 backend for spec compliance.
- Fix the Geode `PFRCPV` and `PFRSQRTV` instruction.
- Fix the SSE 4.2 `CRC32` instruction.

#### C.1.21 Version 2.04

- Sanitize macro handing in the `%error` directive.
- New `%warning` directive to issue user-controlled warnings.
- `%error` directives are now deferred to the final assembly phase.
- New `%fatal` directive to immediately terminate assembly.
- New `%strcat` directive to join quoted strings together.
- New `%use` macro directive to support standard macro directives. See section 4.6.4.
- Excess default parameters to `%macro` now issues a warning by default. See section 4.3.
- Fix `%ifn` and `%elifn`.
- Fix nested `%else` clauses.
- Correct the handling of nested `%rep`s.
- New `%unmacro` directive to undeclare a multi-line macro. See section 4.3.12.
- Builtin macro `__PASS__` which expands to the current assembly pass. See section 4.12.9.
- `__utf16__` and `__utf32__` operators to generate UTF-16 and UTF-32 strings. See section 3.4.5.
- Fix bug in case-insensitive matching when compiled on platforms that don't use the `configure` script. Of the official release binaries, that only affected the OS/2 binary.
- Support for x87 packed BCD constants. See section 3.4.7.
- Correct the `LTR` and `SLDT` instructions in 64-bit mode.
- Fix unnecessary REX.W prefix on indirect jumps in 64-bit mode.
- Add AVX versions of the AES instructions (`VAES`...).
- Fix the 256-bit FMA instructions.
- Add 256-bit AVX stores per the latest AVX spec.
- VIA XCRYPT instructions can now be written either with or without `REP`, apparently different versions of the VIA spec wrote them differently.
- Add missing 64-bit `MOVNTI` instruction.
- Fix the operand size of `VMREAD` and `VMWRITE`.
- Numerous bug fixes, especially to the AES, AVX and VTX instructions.
- The optimizer now always runs until it converges. It also runs even when disabled, but doesn't optimize. This allows most forward references to be resolved properly.
- `%push` no longer needs a context identifier; omitting the context identifier results in an anonymous context.

#### C.1.22 Version 2.03.01

- Fix buffer overflow in the listing module.
- Fix the handling of hexadecimal escape codes in `...` strings.
- The Postscript/PDF documentation has been reformatted.
- The `-F` option now implies `-g`.

#### C.1.23 Version 2.03

- Add support for Intel AVX, CLMUL and FMA instructions, including YMM registers.
- `dy`, `resy` and `yword` for 32-byte operands.
- Fix some SSE5 instructions.
- Intel `INVEPT`, `INVVPID` and `MOVBE` instructions.
- Fix checking for critical expressions when the optimizer is enabled.
- Support the DWARF debugging format for ELF targets.
- Fix optimizations of signed bytes.
- Fix operation on bigendian machines.
- Fix buffer overflow in the preprocessor.
- `SAFESEH` support for Win32, `IMAGEREL` for Win64 (SEH).
- `%?` and `%??` to refer to the name of a macro itself. In particular, `%idefine keyword $%?` can be used to make a keyword "disappear".
- New options for dependency generation: `-MD`, `-MF`, `-MP`, `-MT`, `-MQ`.
- New preprocessor directives `%pathsearch` and `%depend`; INCBIN reimplemented as a macro.
- `%include` now resolves macros in a sane manner.
- `%substr` can now be used to get other than one-character substrings.
- New type of character/string constants, using backquotes (``...``), which support C-style escape sequences.
- `%defstr` and `%idefstr` to stringize macro definitions before creation.
- Fix forward references used in `EQU` statements.

#### C.1.24 Version 2.02

- Additional fixes for MMX operands with explicit `qword`, as well as (hopefully) SSE operands with `oword`.
- Fix handling of truncated strings with `DO`.
- Fix segfaults due to memory overwrites when floating-point constants were used.
- Fix segfaults due to missing include files.
- Fix OpenWatcom Makefiles for DOS and OS/2.
- Add autogenerated instruction list back into the documentation.
- ELF: Fix segfault when generating stabs, and no symbols have been defined.
- ELF: Experimental support for DWARF debugging information.
- New compile date and time standard macros.
- `%ifnum` now returns true for negative numbers.
- New `%iftoken` test for a single token.
- New `%ifempty` test for empty expansion.
- Add support for the `XSAVE` instruction group.
- Makefile for Netware/gcc.
- Fix issue with some warnings getting emitted way too many times.
- Autogenerated instruction list added to the documentation.

#### C.1.25 Version 2.01

- Fix the handling of MMX registers with explicit `qword` tags on memory (broken in 2.00 due to 64-bit changes.)
- Fix the PREFETCH instructions.
- Fix the documentation.
- Fix debugging info when using `-f elf` (backwards compatibility alias for `-f elf32`).
- Man pages for rdoff tools (from the Debian project.)
- ELF: handle large numbers of sections.
- Fix corrupt output when the optimizer runs out of passes.

#### C.1.26 Version 2.00

- Added c99 data-type compliance.
- Added general x86-64 support.
- Added win64 (x86-64 COFF) output format.
- Added `__BITS__` standard macro.
- Renamed the `elf` output format to `elf32` for clarity.
- Added `elf64` and `macho` (MacOS X) output formats.
- Added Numeric constants in `dq` directive.
- Added `oword`, `do` and `reso` pseudo operands.
- Allow underscores in numbers.
- Added 8-, 16- and 128-bit floating-point formats.
- Added binary, octal and hexadecimal floating-point.
- Correct the generation of floating-point constants.
- Added floating-point option control.
- Added Infinity and NaN floating point support.
- Added ELF Symbol Visibility support.
- Added setting OSABI value in ELF header directive.
- Added Generate Makefile Dependencies option.
- Added Unlimited Optimization Passes option.
- Added `%IFN` and `%ELIFN` support.
- Added Logical Negation Operator.
- Enhanced Stack Relative Preprocessor Directives.
- Enhanced ELF Debug Formats.
- Enhanced Send Errors to a File option.
- Added SSSE3, SSE4.1, SSE4.2, SSE5 support.
- Added a large number of additional instructions.
- Significant performance improvements.
- `-w+warning` and `-w-warning` can now be written as -Wwarning and -Wno-warning, respectively. See section 2.1.24.
- Add `-w+error` to treat warnings as errors. See section 2.1.24.
- Add `-w+all` and `-w-all` to enable or disable all suppressible warnings. See section 2.1.24.

### C.2 NASM 0.98 Series

The 0.98 series was the production versions of NASM from 1999 to 2007.

#### C.2.1 Version 0.98.39

- fix buffer overflow
- fix outas86's `.bss` handling
- "make spotless" no longer deletes config.h.in.
- `%(el)if(n)idn` insensitivity to string quotes difference (#809300).
- (nasm.c)`__OUTPUT_FORMAT__` changed to string value instead of symbol.

#### C.2.2 Version 0.98.38

- Add Makefile for 16-bit DOS binaries under OpenWatcom, and modify `mkdep.pl` to be able to generate completely pathless dependencies, as required by OpenWatcom wmake (it supports path searches, but not explicit paths.)
- Fix the `STR` instruction.
- Fix the ELF output format, which was broken under certain circumstances due to the addition of stabs support.
- Quick-fix Borland format debug-info for `-f obj`
- Fix for `%rep` with no arguments (#560568)
- Fix concatenation of preprocessor function call (#794686)
- Fix long label causes coredump (#677841)
- Use autoheader as well as autoconf to keep configure from generating ridiculously long command lines.
- Make sure that all of the formats which support debugging output actually will suppress debugging output when `-g` not specified.

#### C.2.3 Version 0.98.37

- Paths given in `-I` switch searched for `incbin`-ed as well as `%include`-ed files.
- Added stabs debugging for the ELF output format, patch from Martin Wawro.
- Fix `output/outbin.c` to allow origin > 80000000h.
- Make `-U` switch work.
- Fix the use of relative offsets with explicit prefixes, e.g. `a32 loop foo`.
- Remove `backslash()`.
- Fix the `SMSW` and `SLDT` instructions.
- `-O2` and `-O3` are no longer aliases for `-O10` and `-O15`. If you mean the latter, please say so! :)

#### C.2.4 Version 0.98.36

- Update rdoff - librarian/archiver - common rec - docs!
- Fix signed/unsigned problems.
- Fix `JMP FAR label` and `CALL FAR label`.
- Add new multisection support - map files - fix align bug
- Fix sysexit, movhps/movlps reg,reg bugs in insns.dat
- `Q` or `O` suffixes indicate octal
- Support Prescott new instructions (PNI).
- Cyrix `XSTORE` instruction.

#### C.2.5 Version 0.98.35

- Fix build failure on 16-bit DOS (Makefile.bc3 workaround for compiler bug.)
- Fix dependencies and compiler warnings.
- Add "const" in a number of places.
- Add -X option to specify error reporting format (use -Xvc to integrate with Microsoft Visual Studio.)
- Minor changes for code legibility.
- Drop use of tmpnam() in rdoff (security fix.)

#### C.2.6 Version 0.98.34

- Correct additional address-size vs. operand-size confusions.
- Generate dependencies for all Makefiles automatically.
- Add support for unimplemented (but theoretically available) registers such as tr0 and cr5. Segment registers 6 and 7 are called segr6 and segr7 for the operations which they can be represented.
- Correct some disassembler bugs related to redundant address-size prefixes. Some work still remains in this area.
- Correctly generate an error for things like "SEG eax".
- Add the JMPE instruction, enabled by "CPU IA64".
- Correct compilation on newer gcc/glibc platforms.
- Issue an error on things like "jmp far eax".

#### C.2.7 Version 0.98.33

- New __NASM_PATCHLEVEL__ and __NASM_VERSION_ID__ standard macros to round out the version-query macros. version.pl now understands X.YYplWW or X.YY.ZZplWW as a version number, equivalent to X.YY.ZZ.WW (or X.YY.0.WW, as appropriate).
- New keyword "strict" to disable the optimization of specific operands.
- Fix the handing of size overrides with JMP instructions (instructions such as "jmp dword foo".)
- Fix the handling of "ABSOLUTE label", where "label" points into a relocatable segment.
- Fix OBJ output format with lots of externs.
- More documentation updates.
- Add -Ov option to get verbose information about optimizations.
- Undo a braindead change which broke `%elif` directives.
- Makefile updates.

#### C.2.8 Version 0.98.32

- Fix NASM crashing when `%macro` directives were left unterminated.
- Lots of documentation updates.
- Complete rewrite of the PostScript/PDF documentation generator.
- The MS Visual C++ Makefile was updated and corrected.
- Recognize .rodata as a standard section name in ELF.
- Fix some obsolete Perl4-isms in Perl scripts.
- Fix configure.in to work with autoconf 2.5x.
- Fix a couple of "make cleaner" misses.
- Make the normal "./configure && make" work with Cygwin.

#### C.2.9 Version 0.98.31

- Correctly build in a separate object directory again.
- Derive all references to the version number from the version file.
- New standard macros __NASM_SUBMINOR__ and __NASM_VER__ macros.
- Lots of Makefile updates and bug fixes.
- New `%ifmacro` directive to test for multiline macros.
- Documentation updates.
- Fixes for 16-bit OBJ format output.
- Changed the NASM environment variable to NASMENV.

#### C.2.10 Version 0.98.30

- Changed doc files a lot: completely removed old READMExx and Wishlist files, incorporating all information in CHANGES and TODO.
- I waited a long time to rename zoutieee.c to (original) outieee.c
- moved all output modules to output/ subdirectory.
- Added 'make strip' target to strip debug info from nasm & ndisasm.
- Added INSTALL file with installation instructions.
- Added -v option description to nasm man.
- Added dist makefile target to produce source distributions.
- 16-bit support for ELF output format (GNU extension, but useful.)

#### C.2.11 Version 0.98.28

- Fastcooked this for Debian's Woody release: Frank applied the INCBIN bug patch to 0.98.25alt and called it 0.98.28 to not confuse poor little apt-get.

#### C.2.12 Version 0.98.26

- Reorganised files even better from 0.98.25alt

#### C.2.13 Version 0.98.25alt

- Prettified the source tree. Moved files to more reasonable places.
- Added findleak.pl script to misc/ directory.
- Attempted to fix doc.

#### C.2.14 Version 0.98.25

- Line continuation character `\`.
- Docs inadvertantly reverted - "dos packaging".

#### C.2.15 Version 0.98.24p1

- FIXME: Someone, document this please.

#### C.2.16 Version 0.98.24

- Documentation - Ndisasm doc added to Nasm.doc.

#### C.2.17 Version 0.98.23

- Attempted to remove rdoff version1
- Lino Mastrodomenico's patches to preproc.c (%$$ bug?).

#### C.2.18 Version 0.98.22

- Update rdoff2 - attempt to remove v1.

#### C.2.19 Version 0.98.21

- Optimization fixes.

#### C.2.20 Version 0.98.20

- Optimization fixes.

#### C.2.21 Version 0.98.19

- H. J. Lu's patch back out.

#### C.2.22 Version 0.98.18

- Added ".rdata" to "-f win32".

#### C.2.23 Version 0.98.17

- H. J. Lu's "bogus elf" patch. (Red Hat problem?)

#### C.2.24 Version 0.98.16

- Fix whitespace before "[section ..." bug.

#### C.2.25 Version 0.98.15

- Rdoff changes (?).
- Fix fixes to memory leaks.

#### C.2.26 Version 0.98.14

- Fix memory leaks.

#### C.2.27 Version 0.98.13

- There was no 0.98.13

#### C.2.28 Version 0.98.12

- Update optimization (new function of "-O1")
- Changes to test/bintest.asm (?).

#### C.2.29 Version 0.98.11

- Optimization changes.
- Ndisasm fixed.

#### C.2.30 Version 0.98.10

- There was no 0.98.10

#### C.2.31 Version 0.98.09

- Add multiple sections support to "-f bin".
- Changed GLOBAL_TEMP_BASE in outelf.c from 6 to 15.
- Add "-v" as an alias to the "-r" switch.
- Remove "#ifdef" from Tasm compatibility options.
- Remove redundant size-overrides on "mov ds, ex", etc.
- Fixes to SSE2, other insns.dat (?).
- Enable uppercase "I" and "P" switches.
- Case insinsitive "seg" and "wrt".
- Update install.sh (?).
- Allocate tokens in blocks.
- Improve "invalid effective address" messages.

#### C.2.32 Version 0.98.08

- Add "`%strlen`" and "`%substr`" macro operators
- Fixed broken c16.mac.
- Unterminated string error reported.
- Fixed bugs as per 0.98bf

#### C.2.33 Version 0.98.09b with John Coffman patches released 28-Oct-2001

Changes from 0.98.07 release to 98.09b as of 28-Oct-2001

- More closely compatible with 0.98 when -O0 is implied or specified. Not strictly identical, since backward branches in range of short offsets are recognized, and signed byte values with no explicit size specification will be assembled as a single byte.
- More forgiving with the PUSH instruction. 0.98 requires a size to be specified always. 0.98.09b will imply the size from the current BITS setting (16 or 32).
- Changed definition of the optimization flag:

-O0 strict two-pass assembly, JMP and Jcc are handled more like 0.98, except that back- ward JMPs are short, if possible.

-O1 strict two-pass assembly, but forward branches are assembled with code guaranteed to reach; may produce larger code than -O0, but will produce successful assembly more often if branch offset sizes are not specified.

-O2 multi-pass optimization, minimize branch offsets; also will minimize signed immed- iate bytes, overriding size specification.

-O3 like -O2, but more passes taken, if needed

#### C.2.34 Version 0.98.07 released 01/28/01

- Added Stepane Denis' SSE2 instructions to a *working* version of the code - some earlier versions were based on broken code - sorry 'bout that. version "0.98.07"

01/28/01

- Cosmetic modifications to nasm.c, nasm.h, AUTHORS, MODIFIED

#### C.2.35 Version 0.98.06f released 01/18/01

- - Add "metalbrain"s jecxz bug fix in insns.dat - alter nasmdoc.src to match - version "0.98.06f"

#### C.2.36 Version 0.98.06e released 01/09/01

- Removed the "outforms.h" file - it appears to be someone's old backup of "outform.h". version "0.98.06e"

01/09/01

- fbk - finally added the fix for the "multiple %includes bug", known since 7/27/99 - reported originally (?) and sent to us by Austin Lunnen - he reports that John Fine had a fix within the day. Here it is...
- Nelson Rush resigns from the group. Big thanks to Nelson for his leadership and enthusiasm in getting these changes incorporated into Nasm!
- fbk - [list +], [list -] directives - ineptly implemented, should be re-written or removed, perhaps.
- Brian Raiter / fbk - "elfso bug" fix - applied to aoutb format as well - testing might be desirable...

08/07/00

- James Seter - -postfix, -prefix command line switches.
- Yuri Zaporogets - rdoff utility changes.

#### C.2.37 Version 0.98p1

- GAS-like palign (Panos Minos)
- FIXME: Someone, fill this in with details

#### C.2.38 Version 0.98bf (bug-fixed)

- Fixed - elf and aoutb bug - shared libraries - multiple "%include" bug in "-f obj" - jcxz, jecxz bug - unrecognized option bug in ndisasm

#### C.2.39 Version 0.98.03 with John Coffman's changes released 27-Jul-2000

- Added signed byte optimizations for the 0x81/0x83 class of instructions: ADC, ADD, AND, CMP, OR, SBB, SUB, XOR: when used as 'ADD reg16,imm' or 'ADD reg32,imm.' Also optimization of signed byte form of 'PUSH imm' and 'IMUL reg,imm'/'IMUL reg,reg,imm.' No size specification is needed.
- Added multi-pass JMP and Jcc offset optimization. Offsets on forward references will preferentially use the short form, without the need to code a specific size (short or near) for the branch. Added instructions for 'Jcc label' to use the form 'Jnotcc $+3/JMP label', in cases where a short offset is out of bounds. If compiling for a 386 or higher CPU, then the 386 form of Jcc will be used instead.

This feature is controlled by a new command-line switch: "O", (upper case letter O). "-O0" reverts the assembler to no extra optimization passes, "-O1" allows up to 5 extra passes, and "-O2"(default), allows up to 10 extra optimization passes.

- Added a new directive: 'cpu XXX', where XXX is any of: 8086, 186, 286, 386, 486, 586, pentium, 686, PPro, P2, P3 or Katmai. All are case insensitive. All instructions will be selected only if they apply to the selected cpu or lower. Corrected a couple of bugs in cpu-dependence in 'insns.dat'.
- Added to 'standard.mac', the "use16" and "use32" forms of the "bits 16/32" directive. This is nothing new, just conforms to a lot of other assemblers. (minor)
- Changed label allocation from 320/32 (10000 labels @ 200K+) to 32/37 (1000 labels); makes running under DOS much easier. Since additional label space is allocated dynamically, this should have no effect on large programs with lots of labels. The 37 is a prime, believed to be better for hashing. (minor)

#### C.2.40 Version 0.98.03

"Integrated patchfile 0.98-0.98.01. I call this version 0.98.03 for historical reasons: 0.98.02 was trashed." --John Coffman <johninsd@san.rr.com>, 27-Jul-2000

- Kendall Bennett's SciTech MGL changes
- Note that you must define "TASM_COMPAT" at compile-time to get the Tasm Ideal Mode compatibility.
- All changes can be compiled in and out using the TASM_COMPAT macros, and when compiled without TASM_COMPAT defined we get the exact same binary as the unmodified 0.98 sources.
- standard.mac, macros.c: Added macros to ignore TASM directives before first include
- nasm.h: Added extern declaration for tasm_compatible_mode
- nasm.c: Added global variable tasm_compatible_mode
- Added command line switch for TASM compatible mode (-t)
- Changed version command line to reflect when compiled with TASM additions
- Added response file processing to allow all arguments on a single line (response file is @resp rather than -@resp for NASM format).
- labels.c: Changes islocal() macro to support TASM style @@local labels.
- Added islocalchar() macro to support TASM style @@local labels.
- parser.c: Added support for TASM style memory references (ie: mov [DWORD eax],10 rather than the NASM style mov DWORD [eax],10).
- preproc.c: Added new directives, `%arg`, `%local`, `%stacksize` to directives table
- Added support for TASM style directives without a leading % symbol.
- Integrated a block of changes from Andrew Zabolotny <bit@eltech.ru>:
- A new keyword `%xdefine` and its case-insensitive counterpart `%ixdefine`. They work almost the same way as `%define` and `%idefine` but expand the definition immediately, not on the invocation. Something like a cross between `%define` and `%assign`. The "x" suffix stands for "eXpand", so "xdefine" can be deciphered as "expand-and-define". Thus you can do things like this:

         %assign ofs     0

         %macro  arg     1
                 %xdefine %1 dword [esp+ofs]
                 %assign ofs ofs+4
         %endmacro

- Changed the place where the expansion of %$name macros are expanded. Now they are converted into ..@ctxnum.name form when detokenizing, so there are no quirks as before when using %$name arguments to macros, in macros etc. For example:

         %macro  abc     1
                 %define %1 hello
         %endm

         abc     %$here
         %$here

Now last line will be expanded into "hello" as expected. This also allows for lots of goodies, a good example are extended "proc" macros included in this archive.

- Added a check for "cstk" in smacro_defined() before calling get_ctx() - this allows for things like:

         %ifdef %$abc
         %endif

to work without warnings even in no context.

- Added a check for "cstk" in %if*ctx and %elif*ctx directives - this allows to use `%ifctx` without excessive warnings. If there is no active context, `%ifctx` goes through "false" branch.
- Removed "user error: " prefix with `%error` directive: it just clobbers the output and has absolutely no functionality. Besides, this allows to write macros that does not differ from built-in functions in any way.
- Added expansion of string that is output by `%error` directive. Now you can do things like:

         %define hello(x) Hello, x!

         %define %$name andy
         %error "hello(%$name)"

Same happened with `%include` directive.

- Now all directives that expect an identifier will try to expand and concatenate everything without whitespaces in between before usage. For example, with "unfixed" nasm the commands

         %define %$abc hello
         %define __%$abc goodbye
         __%$abc

would produce "incorrect" output: last line will expand to

         hello goodbyehello

Not quite what you expected, eh? :-) The answer is that preprocessor treats the `%define` construct as if it would be

         %define __ %$abc goodbye

(note the white space between __ and %$abc). After my "fix" it will "correctly" expand into

         goodbye

as expected. Note that I use quotes around words "correct", "incorrect" etc because this is rather a feature not a bug; however current behaviour is more logical (and allows more advanced macro usage :-).

Same change was applied to: `%push`,`%macro`,`%imacro`,`%define`,`%idefine`,`%xdefine`,`%ixdefine`, `%assign`,`%iassign`,`%undef`

- A new directive [WARNING {+|-}warning-id] have been added. It works only if the assembly phase is enabled (i.e. it doesn't work with nasm -e).
- A new warning type: macro-selfref. By default this warning is disabled; when enabled NASM warns when a macro self-references itself; for example the following source:

           [WARNING macro-selfref]

           %macro          push    1-*
                   %rep    %0
                           push    %1
                           %rotate 1
                   %endrep
           %endmacro

                           push    eax,ebx,ecx

will produce a warning, but if we remove the first line we won't see it anymore (which is The Right Thing To Do {tm} IMHO since C preprocessor eats such constructs without warnings at all).

- Added a "error" routine to preprocessor which always will set ERR_PASS1 bit in severity_code. This removes annoying repeated errors on first and second passes from preprocessor.
- Added the %+ operator in single-line macros for concatenating two identifiers. Usage example:

           %define _myfunc _otherfunc
           %define cextern(x) _ %+ x
           cextern (myfunc)

After first expansion, third line will become "_myfunc". After this expansion is performed again so it becomes "_otherunc".

- Now if preprocessor is in a non-emitting state, no warning or error will be emitted. Example:

           %if 1
                   mov     eax,ebx
           %else
                   put anything you want between these two brackets,
                   even macro-parameter references %1 or local
                   labels %$zz or macro-local labels %%zz - no
                   warning will be emitted.
           %endif

- Context-local variables on expansion as a last resort are looked up in outer contexts. For example, the following piece:

           %push   outer
           %define %$a [esp]

                   %push   inner
                   %$a
                   %pop
           %pop

will expand correctly the fourth line to [esp]; if we'll define another %$a inside the "inner" context, it will take precedence over outer definition. However, this modification has been applied only to expand_smacro and not to smacro_define: as a consequence expansion looks in outer contexts, but `%ifdef` won't look in outer contexts.

This behaviour is needed because we don't want nested contexts to act on already defined local macros. Example:

           %define %$arg1  [esp+4]
           test    eax,eax
           if      nz
                   mov     eax,%$arg1
           endif

In this example the "if" mmacro enters into the "if" context, so %$arg1 is not valid anymore inside "if". Of course it could be worked around by using explicitely %$$arg1 but this is ugly IMHO.

- Fixed memory leak in `%undef`. The origline wasn't freed before exiting on success.
- Fixed trap in preprocessor when line expanded to empty set of tokens. This happens, for example, in the following case:

           #define SOMETHING
           SOMETHING

#### C.2.41 Version 0.98

All changes since NASM 0.98p3 have been produced by H. Peter Anvin <hpa@zytor.com>.

- The documentation comment delimiter is
- Allow EQU definitions to refer to external labels; reported by Pedro Gimeno.
- Re-enable support for RDOFF v1; reported by Pedro Gimeno.
- Updated License file per OK from Simon and Julian.

#### C.2.42 Version 0.98p9

- Update documentation (although the instruction set reference will have to wait; I don't want to hold up the 0.98 release for it.)
- Verified that the NASM implementation of the PEXTRW and PMOVMSKB instructions is correct. The encoding differs from what the Intel manuals document, but the Pentium III behaviour matches NASM, not the Intel manuals.
- Fix handling of implicit sizes in PSHUFW and PINSRW, reported by Stefan Hoffmeister.
- Resurrect the -s option, which was removed when changing the diagnostic output to stdout.

#### C.2.43 Version 0.98p8

- Fix for "DB" when NASM is running on a bigendian machine.
- Invoke insns.pl once for each output script, making Makefile.in legal for "make -j".
- Improve the Unix configure-based makefiles to make package creation easier.
- Included an RPM .spec file for building RPM (RedHat Package Manager) packages on Linux or Unix systems.
- Fix Makefile dependency problems.
- Change src/rdsrc.pl to include sectioning information in info output; required for install-info to work.
- Updated the RDOFF distribution to version 2 from Jules; minor massaging to make it compile in my environment.
- Split doc files that can be built by anyone with a Perl interpreter off into a separate archive.
- "Dress rehearsal" release!

#### C.2.44 Version 0.98p7

- Fixed opcodes with a third byte-sized immediate argument to not complain if given "byte" on the immediate.
- Allow `%undef` to remove single-line macros with arguments. This matches the behaviour of #undef in the C preprocessor.
- Allow -d, -u, -i and -p to be specified as -D, -U, -I and -P for compatibility with most C compilers and preprocessors. This allows Makefile options to be shared between cc and nasm, for example.
- Minor cleanups.
- Went through the list of Katmai instructions and hopefully fixed the (rather few) mistakes in it.
- (Hopefully) fixed a number of disassembler bugs related to ambiguous instructions (disambiguated by -p) and SSE instructions with REP.
- Fix for bug reported by Mark Junger: "call dword 0x12345678" should work and may add an OSP (affected CALL, JMP, Jcc).
- Fix for environments when "stderr" isn't a compile-time constant.

#### C.2.45 Version 0.98p6

- Took officially over coordination of the 0.98 release; so drop the p3.x notation. Skipped p4 and p5 to avoid confusion with John Fine's J4 and J5 releases.
- Update the documentation; however, it still doesn't include documentation for the various new instructions. I somehow wonder if it makes sense to have an instruction set reference in the assembler manual when Intel et al have PDF versions of their manuals online.
- Recognize "idt" or "centaur" for the -p option to ndisasm.
- Changed error messages back to stderr where they belong, but add an -E option to redirect them elsewhere (the DOS shell cannot redirect stderr.)
- -M option to generate Makefile dependencies (based on code from Alex Verstak.)
- `%undef` preprocessor directive, and -u option, that undefines a single-line macro.
- OS/2 Makefile (Mkfiles/Makefile.os2) for Borland under OS/2; from Chuck Crayne.
- Various minor bugfixes (reported by): - Dangling `%s` in preproc.c (Martin Junker)
- THERE ARE KNOWN BUGS IN SSE AND THE OTHER KATMAI INSTRUCTIONS. I am on a trip and didn't bring the Katmai instruction reference, so I can't work on them right now.
- Updated the License file per agreement with Simon and Jules to include a GPL distribution clause.

#### C.2.46 Version 0.98p3.7

- (Hopefully) fixed the canned Makefiles to include the outrdf2 and zoutieee modules.
- Renamed changes.asm to changed.asm.

#### C.2.47 Version 0.98p3.6

- Fixed a bunch of instructions that were added in 0.98p3.5 which had memory operands, and the address-size prefix was missing from the instruction pattern.

#### C.2.48 Version 0.98p3.5

- Merged in changes from John S. Fine's 0.98-J5 release. John's based 0.98-J5 on my 0.98p3.3 release; this merges the changes.
- Expanded the instructions flag field to a long so we can fit more flags; mark SSE (KNI) and AMD or Katmai-specific instructions as such.
- Fix the "PRIV" flag on a bunch of instructions, and create new "PROT" flag for protected-mode-only instructions (orthogonal to if the instruction is privileged!) and new "SMM" flag for SMM-only instructions.
- Added AMD-only SYSCALL and SYSRET instructions.
- Make SSE actually work, and add new Katmai MMX instructions.
- Added a -p (preferred vendor) option to ndisasm so that it can distinguish e.g. Cyrix opcodes also used in SSE. For example:

         ndisasm -p cyrix aliased.bin
         00000000  670F514310        paddsiw mm0,[ebx+0x10]
         00000005  670F514320        paddsiw mm0,[ebx+0x20]
         ndisasm -p intel aliased.bin
         00000000  670F514310        sqrtps xmm0,[ebx+0x10]
         00000005  670F514320        sqrtps xmm0,[ebx+0x20]

- Added a bunch of Cyrix-specific instructions.

#### C.2.49 Version 0.98p3.4

- Made at least an attempt to modify all the additional Makefiles (in the Mkfiles directory). I can't test it, but this was the best I could do.
- DOS DJGPP+"Opus Make" Makefile from John S. Fine.
- changes.asm changes from John S. Fine.

#### C.2.50 Version 0.98p3.3

- Patch from Conan Brink to allow nesting of `%rep` directives.
- If we're going to allow INT01 as an alias for INT1/ICEBP (one of Jules 0.98p3 changes), then we should allow INT03 as an alias for INT3 as well.
- Updated changes.asm to include the latest changes.
- Tried to clean up the <CR>s that had snuck in from a DOS/Windows environment into my Unix environment, and try to make sure than DOS/Windows users get them back.
- We would silently generate broken tools if insns.dat wasn't sorted properly. Change insns.pl so that the order doesn't matter.
- Fix bug in insns.pl (introduced by me) which would cause conditional instructions to have an extra "cc" in disassembly, e.g. "jnz" disassembled as "jccnz".

#### C.2.51 Version 0.98p3.2

- Merged in John S. Fine's changes from his 0.98-J4 prerelease; see http://www.csoft.net/cz/johnfine/
- Changed previous "spotless" Makefile target (appropriate for distribution) to "distclean", and added "cleaner" target which is same as "clean" except deletes files generated by Perl scripts; "spotless" is union.
- Removed BASIC programs from distribution. Get a Perl interpreter instead (see below.)
- Calling this "pre-release 3.2" rather than "p3-hpa2" because of John's contributions.
- Actually link in the IEEE output format (zoutieee.c); fix a bunch of compiler warnings in that file. Note I don't know what IEEE output is supposed to look like, so these changes were made "blind".

#### C.2.52 Version 0.98p3-hpa

- Merged nasm098p3.zip with nasm-0.97.tar.gz to create a fully buildable version for Unix systems (Makefile.in updates, etc.)
- Changed insns.pl to create the instruction tables in nasm.h and names.c, so that a new instruction can be added by adding it *only* to insns.dat.
- Added the following new instructions: SYSENTER, SYSEXIT, FXSAVE, FXRSTOR, UD1, UD2 (the latter two are two opcodes that Intel guarantee will never be used; one of them is documented as UD2 in Intel documentation, the other one just as "Undefined Opcode" -- calling it UD1 seemed to make sense.)
- MAX_SYMBOL was defined to be 9, but LOADALL286 and LOADALL386 are 10 characters long. Now MAX_SYMBOL is derived from insns.dat.
- A note on the BASIC programs included: forget them. insns.bas is already out of date. Get yourself a Perl interpreter for your platform of choice at http://www.cpan.org/ports/index.html.

#### C.2.53 Version 0.98 pre-release 3

- added response file support, improved command line handling, new layout help screen
- fixed limit checking bug, 'OUT byte nn, reg' bug, and a couple of rdoff related bugs, updated Wishlist; 0.98 Prerelease 3.

#### C.2.54 Version 0.98 pre-release 2

- fixed bug in outcoff.c to do with truncating section names longer than 8 characters, referencing beyond end of string; 0.98 pre-release 2

#### C.2.55 Version 0.98 pre-release 1

- Fixed a bug whereby STRUC didn't work at all in RDF.
- Fixed a problem with group specification in PUBDEFs in OBJ.
- Improved ease of adding new output formats. Contribution due to Fox Cutter.
- Fixed a bug in relocations in the `bin' format: was showing up when a relocatable reference crossed an 8192-byte boundary in any output section.
- Fixed a bug in local labels: local-label lookups were inconsistent between passes one and two if an EQU occurred between the definition of a global label and the subsequent use of a local label local to that global.
- Fixed a seg-fault in the preprocessor (again) which happened when you use a blank line as the first line of a multi-line macro definition and then defined a label on the same line as a call to that macro.
- Fixed a stale-pointer bug in the handling of the NASM environment variable. Thanks to Thomas McWilliams.
- ELF had a hard limit on the number of sections which caused segfaults when transgressed. Fixed.
- Added ability for ndisasm to read from stdin by using `-' as the filename.
- ndisasm wasn't outputting the TO keyword. Fixed.
- Fixed error cascade on bogus expression in `%if` - an error in evaluation was causing the entire `%if` to be discarded, thus creating trouble later when the `%else` or `%endif` was encountered.
- Forward reference tracking was instruction-granular not operand- granular, which was causing 286-specific code to be generated needlessly on code of the form `shr word [forwardref],1'. Thanks to Jim Hague for sending a patch.
- All messages now appear on stdout, as sending them to stderr serves no useful purpose other than to make redirection difficult.
- Fixed the problem with EQUs pointing to an external symbol - this now generates an error message.
- Allowed multiple size prefixes to an operand, of which only the first is taken into account.
- Incorporated John Fine's changes, including fixes of a large number of preprocessor bugs, some small problems in OBJ, and a reworking of label handling to define labels before their line is assembled, rather than after.
- Reformatted a lot of the source code to be more readable. Included 'coding.txt' as a guideline for how to format code for contributors.
- Stopped nested `%reps` causing a panic - they now cause a slightly more friendly error message instead.
- Fixed floating point constant problems (patch by Pedro Gimeno)
- Fixed the return value of insn_size() not being checked for -1, indicating an error.
- Incorporated 3Dnow! instructions.
- Fixed the 'mov eax, eax + ebx' bug.
- Fixed the GLOBAL EQU bug in ELF. Released developers release 3.
- Incorporated John Fine's command line parsing changes
- Incorporated David Lindauer's OMF debug support
- Made changes for LCC 4.0 support (`__NASM_CDecl__`, removed register size specification warning when sizes agree).

### C.3 NASM 0.9 Series

Revisions before 0.98.

#### C.3.1 Version 0.97 released December 1997

- This was entirely a bug-fix release to 0.96, which seems to have got cursed. Silly me.
- Fixed stupid mistake in OBJ which caused `MOV EAX,<constant>' to fail. Caused by an error in the `MOV EAX,<segment>' support.
- ndisasm hung at EOF when compiled with lcc on Linux because lcc on Linux somehow breaks feof(). ndisasm now does not rely on feof().
- A heading in the documentation was missing due to a markup error in the indexing. Fixed.
- Fixed failure to update all pointers on realloc() within extended- operand code in parser.c. Was causing wrong behaviour and seg faults on lines such as `dd 0.0,0.0,0.0,0.0,...'
- Fixed a subtle preprocessor bug whereby invoking one multi-line macro on the first line of the expansion of another, when the second had been invoked with a label defined before it, didn't expand the inner macro.
- Added internal.doc back in to the distribution archives - it was missing in 0.96 *blush*
- Fixed bug causing 0.96 to be unable to assemble its own test files, specifically objtest.asm. *blush again*
- Fixed seg-faults and bogus error messages caused by mismatching `%rep` and `%endrep` within multi-line macro definitions.
- Fixed a problem with buffer overrun in OBJ, which was causing corruption at ends of long PUBDEF records.
- Separated DOS archives into main-program and documentation to reduce download size.

#### C.3.2 Version 0.96 released November 1997

- Fixed a bug whereby, if `nasm sourcefile' would cause a filename collision warning and put output into `nasm.out', then `nasm sourcefile -o outputfile' still gave the warning even though the `-o' was honoured. Fixed name pollution under Digital UNIX: one of its header files defined R_SP, which broke the enum in nasm.h.
- Fixed minor instruction table problems: FUCOM and FUCOMP didn't have two-operand forms; NDISASM didn't recognise the longer register forms of PUSH and POP (eg FF F3 for PUSH BX); TEST mem,imm32 was flagged as undocumented; the 32-bit forms of CMOV had 16-bit operand size prefixes; `AAD imm' and `AAM imm' are no longer flagged as undocumented because the Intel Architecture reference documents them.
- Fixed a problem with the local-label mechanism, whereby strange types of symbol (EQUs, auto-defined OBJ segment base symbols) interfered with the `previous global label' value and screwed up local labels.
- Fixed a bug whereby the stub preprocessor didn't communicate with the listing file generator, so that the -a and -l options in conjunction would produce a useless listing file.
- Merged `os2' object file format back into `obj', after discovering that `obj' _also_ shouldn't have a link pass separator in a module containing a non-trivial MODEND. Flat segments are now declared using the FLAT attribute. `os2' is no longer a valid object format name: use `obj'.
- Removed the fixed-size temporary storage in the evaluator. Very very long expressions (like `mov ax,1+1+1+1+...' for two hundred 1s or so) should now no longer crash NASM.
- Fixed a bug involving segfaults on disassembly of MMX instructions, by changing the meaning of one of the operand-type flags in nasm.h. This may cause other apparently unrelated MMX problems; it needs to be tested thoroughly.
- Fixed some buffer overrun problems with large OBJ output files. Thanks to DJ Delorie for the bug report and fix.
- Made preprocess-only mode actually listen to the `%line` markers as it prints them, so that it can report errors more sanely.
- Re-designed the evaluator to keep more sensible track of expressions involving forward references: can now cope with previously-nightmare situations such as:

      mov ax,foo | bar
      foo equ 1
      bar equ 2

- Added the ALIGN and ALIGNB standard macros.
- Added PIC support in ELF: use of WRT to obtain the four extra relocation types needed.
- Added the ability for output file formats to define their own extensions to the GLOBAL, COMMON and EXTERN directives.
- Implemented common-variable alignment, and global-symbol type and size declarations, in ELF.
- Implemented NEAR and FAR keywords for common variables, plus far-common element size specification, in OBJ.
- Added a feature whereby EXTERNs and COMMONs in OBJ can be given a default WRT specification (either a segment or a group).
- Transformed the Unix NASM archive into an auto-configuring package.
- Added a sanity-check for people applying SEG to things which are already segment bases: this previously went unnoticed by the SEG processing and caused OBJ-driver panics later.
- Added the ability, in OBJ format, to deal with `MOV EAX,<segment>' type references: OBJ doesn't directly support dword-size segment base fixups, but as long as the low two bytes of the constant term are zero, a word-size fixup can be generated instead and it will work.
- Added the ability to specify sections' alignment requirements in Win32 object files and pure binary files.
- Added preprocess-time expression evaluation: the `%assign` (and `%iassign`) directive and the bare `%if` (and `%elif`) conditional. Added relational operators to the evaluator, for use only in `%if` constructs: the standard relationals = < > <= >= <> (and C-like synonyms == and !=) plus low-precedence logical operators &&, ^^ and ||.
- Added a preprocessor repeat construct: `%rep` / `%exitrep` / `%endrep`.
- Added the __FILE__ and __LINE__ standard macros.
- Added a sanity check for number constants being greater than 0xFFFFFFFF. The warning can be disabled.
- Added the %0 token whereby a variadic multi-line macro can tell how many parameters it's been given in a specific invocation.
- Added `%rotate`, allowing multi-line macro parameters to be cycled.
- Added the `*' option for the maximum parameter count on multi-line macros, allowing them to take arbitrarily many parameters.
- Added the ability for the user-level forms of EXTERN, GLOBAL and COMMON to take more than one argument.
- Added the IMPORT and EXPORT directives in OBJ format, to deal with Windows DLLs.
- Added some more preprocessor `%if` constructs: `%ifidn` / `%ifidni` (exact textual identity), and `%ifid` / `%ifnum` / `%ifstr` (token type testing).
- Added the ability to distinguish SHL AX,1 (the 8086 version) from SHL AX,BYTE 1 (the 286-and-upwards version whose constant happens to be 1).
- Added NetBSD/FreeBSD/OpenBSD's variant of a.out format, complete with PIC shared library features.
- Changed NASM's idiosyncratic handling of FCLEX, FDISI, FENI, FINIT, FSAVE, FSTCW, FSTENV, and FSTSW to bring it into line with the otherwise accepted standard. The previous behaviour, though it was a deliberate feature, was a deliberate feature based on a misunderstanding. Apologies for the inconvenience.
- Improved the flexibility of ABSOLUTE: you can now give it an expression rather than being restricted to a constant, and it can take relocatable arguments as well.
- Added the ability for a variable to be declared as EXTERN multiple times, and the subsequent definitions are just ignored.
- We now allow instruction prefixes (CS, DS, LOCK, REPZ etc) to be alone on a line (without a following instruction).
- Improved sanity checks on whether the arguments to EXTERN, GLOBAL and COMMON are valid identifiers.
- Added misc/exebin.mac to allow direct generation of .EXE files by hacking up an EXE header using DB and DW; also added test/binexe.asm to demonstrate the use of this. Thanks to Yann Guidon for contributing the EXE header code.
- ndisasm forgot to check whether the input file had been successfully opened. Now it does. Doh!
- Added the Cyrix extensions to the MMX instruction set.
- Added a hinting mechanism to allow [EAX+EBX] and [EBX+EAX] to be assembled differently. This is important since [ESI+EBP] and [EBP+ESI] have different default base segment registers.
- Added support for the PharLap OMF extension for 4096-byte segment alignment.

#### C.3.3 Version 0.95 released July 1997

- Fixed yet another ELF bug. This one manifested if the user relied on the default segment, and attempted to define global symbols without first explicitly declaring the target segment.
- Added makefiles (for NASM and the RDF tools) to build Win32 console apps under Symantec C++. Donated by Mark Junker.
- Added `macros.bas' and `insns.bas', QBasic versions of the Perl scripts that convert `standard.mac' to `macros.c' and convert `insns.dat' to `insnsa.c' and `insnsd.c'. Also thanks to Mark Junker.
- Changed the diassembled forms of the conditional instructions so that JB is now emitted as JC, and other similar changes. Suggested list by Ulrich Doewich.
- Added `@' to the list of valid characters to begin an identifier with.
- Documentary changes, notably the addition of the `Common Problems' section in nasm.doc.
- Fixed a bug relating to 32-bit PC-relative fixups in OBJ.
- Fixed a bug in perm_copy() in labels.c which was causing exceptions in cleanup_labels() on some systems.
- Positivity sanity check in TIMES argument changed from a warning to an error following a further complaint.
- Changed the acceptable limits on byte and word operands to allow things like `~10111001b' to work.
- Fixed a major problem in the preprocessor which caused seg-faults if macro definitions contained blank lines or comment-only lines.
- Fixed inadequate error checking on the commas separating the arguments to `db', `dw' etc.
- Fixed a crippling bug in the handling of macros with operand counts defined with a `+' modifier.
- Fixed a bug whereby object file formats which stored the input file name in the output file (such as OBJ and COFF) weren't doing so correctly when the output file name was specified on the command line.
- Removed [INC] and [INCLUDE] support for good, since they were obsolete anyway.
- Fixed a bug in OBJ which caused all fixups to be output in 16-bit (old-format) FIXUPP records, rather than putting the 32-bit ones in FIXUPP32 (new-format) records.
- Added, tentatively, OS/2 object file support (as a minor variant on OBJ).
- Updates to Fox Cutter's Borland C makefile, Makefile.bc2.
- Removed a spurious second fclose() on the output file.
- Added the `-s' command line option to redirect all messages which would go to stderr (errors, help text) to stdout instead.
- Added the `-w' command line option to selectively suppress some classes of assembly warning messages.
- Added the `-p' pre-include and `-d' pre-define command-line options.
- Added an include file search path: the `-i' command line option.
- Fixed a silly little preprocessor bug whereby starting a line with a `%!' environment-variable reference caused an `unknown directive' error.
- Added the long-awaited listing file support: the `-l' command line option.
- Fixed a problem with OBJ format whereby, in the absence of any explicit segment definition, non-global symbols declared in the implicit default segment generated spurious EXTDEF records in the output.
- Added the NASM environment variable.
- From this version forward, Win32 console-mode binaries will be included in the DOS distribution in addition to the 16-bit binaries. Added Makefile.vc for this purpose.
- Added `return 0;' to test/objlink.c to prevent compiler warnings.
- Added the __NASM_MAJOR__ and __NASM_MINOR__ standard defines.
- Added an alternative memory-reference syntax in which prefixing an operand with `&' is equivalent to enclosing it in square brackets, at the request of Fox Cutter.
- Errors in pass two now cause the program to return a non-zero error code, which they didn't before.
- Fixed the single-line macro cycle detection, which didn't work at all on macros with no parameters (caused an infinite loop). Also changed the behaviour of single-line macro cycle detection to work like cpp, so that macros like `extrn' as given in the documentation can be implemented.
- Fixed the implementation of WRT, which was too restrictive in that you couldn't do `mov ax,[di+abc wrt dgroup]' because (di+abc) wasn't a relocatable reference.

#### C.3.4 Version 0.94 released April 1997

- Major item: added the macro processor.
- Added undocumented instructions SMI, IBTS, XBTS and LOADALL286. Also reorganised CMPXCHG instruction into early-486 and Pentium forms. Thanks to Thobias Jones for the information.
- Fixed two more stupid bugs in ELF, which were causing `ld' to continue to seg-fault in a lot of non-trivial cases.
- Fixed a seg-fault in the label manager.
- Stopped FBLD and FBSTP from _requiring_ the TWORD keyword, which is the only option for BCD loads/stores in any case.
- Ensured FLDCW, FSTCW and FSTSW can cope with the WORD keyword, if anyone bothers to provide it. Previously they complained unless no keyword at all was present.
- Some forms of FDIV/FDIVR and FSUB/FSUBR were still inverted: a vestige of a bug that I thought had been fixed in 0.92. This was fixed, hopefully for good this time...
- Another minor phase error (insofar as a phase error can _ever_ be minor) fixed, this one occurring in code of the form

      rol ax,forward_reference
      forward_reference equ 1

- The number supplied to TIMES is now sanity-checked for positivity, and also may be greater than 64K (which previously didn't work on 16-bit systems).
- Added Watcom C makefiles, and misc/pmw.bat, donated by Dominik Behr.
- Added the INCBIN pseudo-opcode.
- Due to the advent of the preprocessor, the [INCLUDE] and [INC] directives have become obsolete. They are still supported in this version, with a warning, but won't be in the next.
- Fixed a bug in OBJ format, which caused incorrect object records to be output when absolute labels were made global.
- Updates to RDOFF subdirectory, and changes to outrdf.c.

#### C.3.5 Version 0.93 released January 1997

This release went out in a great hurry after semi-crippling bugs were found in 0.92.

- Really did fix the stack overflows this time. *blush*
- Had problems with EA instruction sizes changing between passes, when an offset contained a forward reference and so 4 bytes were allocated for the offset in pass one; by pass two the symbol had been defined and happened to be a small absolute value, so only 1 byte got allocated, causing instruction size mismatch between passes and hence incorrect address calculations. Fixed.
- Stupid bug in the revised ELF section generation fixed (associated string-table section for .symtab was hard-coded as 7, even when this didn't fit with the real section table). Was causing `ld' to seg-fault under Linux.
- Included a new Borland C makefile, Makefile.bc2, donated by Fox Cutter <lmb@comtch.iea.com>.

#### C.3.6 Version 0.92 released January 1997

- The FDIVP/FDIVRP and FSUBP/FSUBRP pairs had been inverted: this was fixed. This also affected the LCC driver.
- Fixed a bug regarding 32-bit effective addresses of the form `[other_register+ESP]`.
- Documentary changes, notably documentation of the fact that Borland Win32 compilers use `obj' rather than `win32' object format.
- Fixed the COMENT record in OBJ files, which was formatted incorrectly.
- Fixed a bug causing segfaults in large RDF files.
- OBJ format now strips initial periods from segment and group definitions, in order to avoid complications with the local label syntax.
- Fixed a bug in disassembling far calls and jumps in NDISASM.
- Added support for user-defined sections in COFF and ELF files.
- Compiled the DOS binaries with a sensible amount of stack, to prevent stack overflows on any arithmetic expression containing parentheses.
- Fixed a bug in handling of files that do not terminate in a newline.

#### C.3.7 Version 0.91 released November 1996

- Loads of bug fixes.
- Support for RDF added.
- Support for DBG debugging format added.
- Support for 32-bit extensions to Microsoft OBJ format added.
- Revised for Borland C: some variable names changed, makefile added.
- LCC support revised to actually work.
- JMP/CALL NEAR/FAR notation added.
- `a16', `o16', `a32' and `o32' prefixes added.
- Range checking on short jumps implemented.
- MMX instruction support added.
- Negative floating point constant support added.
- Memory handling improved to bypass 64K barrier under DOS.
- `$` prefix to force treatment of reserved words as identifiers added.
- Default-size mechanism for object formats added.
- Compile-time configurability added.
- `#`, `@`, `~` and c{?} are now valid characters in labels.
- `-e` and `-k` options in NDISASM added.

#### C.3.8 Version 0.90 released October 1996

First release version. First support for object file output. Other changes from previous version (0.3x) too numerous to document.

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