Open Watcom Assembler

Open Watcom Assembler
Original author(s)	Open Watcom Assembler
Operating system	DOS for x86-based PCs, Microsoft Windows, Linux for x86-based PCs, OS/2 for x86-based PCs, FreeBSD for x86-based PCs.
Available in	English
Type	x86 assembler
Website	www.openwatcom.com

Open Watcom Assembler or WASM is an x86 assembler produced by Watcom, based on the Watcom Assembler found in Watcom C/C++ compiler and Watcom FORTRAN 77.^[1]^[2]^[3] Further development is being done on the 32- and 64-bit JWASM project,^[4] which more closely matches the syntax of Microsoft's assembler.^[5]

There are experimental assemblers for PowerPC, Alpha AXP, and MIPS.^[6]

Technical details

Assembler

Native support for output formats Intel OMF output formats
Supports Intel x86 (Pentium MMX, Pentium III-4, 3DNow!, SSE and SSE2) instruction sets.
Supports Microsoft macro assembler (MASM) 5 and 6 syntax (incomplete).^[6]

Disassembler

There is an associated Watcom disassembler, wdis. The assembler does not have listing facilities; instead the use of wdis for generating listings is recommended.^[7] wdis can read OMF, COFF and ELF object files and PE and ELF executables. It supports 16-bit and 32-bit x86 instruction set including MMX, 3DNow!, SSE, SSE2, and SSE3. Support for PowerPC, Alpha AXP, MIPS, and SPARC V8 instruction sets is also built in.^[8]

WASM forks

JWasm

JWasm is a fork of Wasm originated by Japheth with following features:

Native support for output formats Intel OMF (16/32-bit), MS Coff (32-bit and 64-bit), Elf (32-bit and 64-bit), Bin and DOS MZ.
Precompiled JWasm binaries are available for DOS, Windows and Linux. For OS/2 and FreeBSD, makefiles are supplied.
Supports Intel x86 (8086, 80186, 80286, 80386, 80486, Pentium, Pentium Pro), x86-64 instruction sets with SIMD (MMX, 3DNow!, SSE, SSE2, SSE3 and SSSE3, SSE4.1/2 (since Jwasm), AVX (since JWasm 2.06), VMX (Intel VT-x; AMD SVM, the latter though already implemented, currently still inactive) extensions (since JWasm 2.09)).
JWasm is written in C. The source is portable and has successfully been tested with Open Watcom, MS VC, GCC and more.
On Windows, JWasm can be used with both Win32Inc and Masm32. Since v2.01, it will also work with Sven B. Schreiber's SBS WALK32 Win32 Assembly Language Kit^[9]
C header files can be converted to include files for JWasm with Japheth's own dedicated h2incX.
JWasm's source code is released under the Sybase Open Watcom Public License, which allows free commercial and non-commercial use.
Fully supports Microsoft macro assembler 6 syntax, all MASM 8 instructions sets.

Japheth paused development (or rather, was out of contact) of JWASM in January 2014 with version 2.12pre, but currently continues work on project on GitHub,^[10] current (June 2024) version is 2.18. Also, others on the Masm32 forum^[11] picked up where Japheth once left off.

HJWasm

HJWasm, adding the prefix H in reference to Masm32 forum member Habran who started off this second WASM development continuation. Version 2.13pre was originally announced in 2016.^[12] New features include:

Instructions:

SIMD:

MMX: MOVQ and added in 2.13, to supplement MOVD.
AVX2: VGATHERDPD, VGATHERQPD, VGATHERDPS, VGATHERQPS, VPGATHERDD, VPGATHERQD, VPGATHERDQ, VPGATHERQQ, VEX-encoded general purpose instructions added in 2.13. Remaining instructions added in 2.16.
AVX-512: VCMPxxPD, VCMPxxPS, VCMPxxSD, VCMPxxPD, VCMPxxSS, AVX-512F set, EVEX-encoded instructions added in 2.13; VMOVQ added 2.13, to supplement MOVD. Remaining instructions added in 2.16.

Random Number Generator: RDRAND, RDSEED added in 2.13.
half-precision conversions: F16C(VCVTPH2PS, VCVTPS2PH) added in 2.13.
Intel MPX: Added in 2.31.

Registers: RIP, ZMM registers added in 2.13.
OO language extension added in 2.25.

HASM

HASM is a renamed version of HJWASM, starting in version 2.33. The name was used following a MASM Forum discussion thread that originally proposed a replacement name. The name HASM was proposed by forum member habran in Reply #6,^[13] and was finalized at the end of discussion thread at Reply #33.^[14] No known features are added in HASM's release cycle.

UASM

The name was actually used in version 2.33 (dated 2017-05-20) at Terraspace ltd's product page,^[15] but it was only announced in version 2.34.^[16] Changes to HJWASM includes:^[17]

Instruction sets: RDPID added in 2.38.

AVX-512: VAESDEC added in 2.38
Data transfer: MOVBE added in 2.47. MOVABS added in 2.48.
Intel ADX: ADCX, ADOX added in 2.38
Intel MPX: Support of BND prefix added in 2.34. BND prefix removed from JCXZ instruction group in 2.40.
CLMUL instruction set: Added in 2.46.8, including pseudo-op forms of CLMUL.
Hashing: SHA instruction set added in 2.46.8.
Supervisor Mode Access Prevention: CLAC added in 2.38.
Persistent Memory Extensions: CLFLUSHOPT added in 2.38.

Addressing modes: 64bit absolute immediate (2.37)
Identified types

Record types: fully supports registers and up to 32bit record fields in 2.41.

Support for 128bit: Added in 2.42, inline declaration with the type added in 2.43.1 / .2.

Support of typedef chain on return types added in 2.46.8.
m512 built-in types added in 2.47.

Console colour coding: Added for Windows, OSX and Linux in 2.43.1 / .2.
Function calling: C-style function calling added in 2.46.

References

^ Randall Hyde. "WASM: The Open Watcom Assembler". Archived from the original on 2012-03-02. Retrieved 2017-09-11.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
^ Leiterman, James (2005). "MASM vs. NASM vs. TASM vs. WASM". 32/64-bit 80x86 assembly language architecture. Wordware Publishing, Inc. p. 481. ISBN 978-1-59822-002-5. Retrieved 2010-02-01.
^ Leiterman p482 on Google Books
^ JWASM, a 32/64 bit assembler based on WASM with syntax similar to MASM. Archived 10 October 2014
^ Fog, Agner (2009), Optimizing subroutines in assembly language (PDF) (2009-09-26 ed.), p. 13
^ ^a ^b Open Watcom website: Assembler Archived 2006-07-15 at the Wayback Machine
^ OpenWatcom: "No listing files are generated [by the assembler]. Producing full listings may be a waste of effort because wdis (the Open Watcom disassembler) does a very good job. However, it could be extremely helpful to produce a dump of the internal symbol table the way MASM does, especially for diagnostic purposes."
^ Open Watcom website: Disassembler Archived 2006-07-15 at the Wayback Machine
^
The 1996 "WALK32 consists of the following main components:
- A full-featured PE (Portable Executable) file linker called W32Link.
- A main include file, containing Win32 constant, type, and structure definitions.
- Another include file, containing the application and DLL startup source code.
- Segment and PE section management macros.
- Macros related to Unicode support.
- Several demo applications and DLL’s.
- A collection of programming utilities for various purposes." walk32.doc in walk32_1.zip
^ GitHub/Baron-von-Riedesel/JWasm
^ UASM Assembler Development
^ HJWasm Releases
^ A New Name? (thread page 1)
^ A New Name? (thread page 3)
^ UASM (2.33)
^ UASM 2.33 Release
^ UASM ChangeLog

External links

WASM assembler wiki
JWasm
Terraspace ltd pages: HJWASM, Hasm, UASM

[1] Randall Hyde. "WASM: The Open Watcom Assembler". Archived from the original on 2012-03-02. Retrieved 2017-09-11.{{cite web}}: CS1 maint: bot: original URL status unknown (link)

[2] Leiterman, James (2005). "MASM vs. NASM vs. TASM vs. WASM". 32/64-bit 80x86 assembly language architecture. Wordware Publishing, Inc. p. 481. ISBN 978-1-59822-002-5. Retrieved 2010-02-01.

[3] Leiterman p482 on Google Books

[4] JWASM, a 32/64 bit assembler based on WASM with syntax similar to MASM. Archived 10 October 2014

[5] Fog, Agner (2009), Optimizing subroutines in assembly language (PDF) (2009-09-26 ed.), p. 13

[wasmsite-6] Open Watcom website: Assembler Archived 2006-07-15 at the Wayback Machine

[7] OpenWatcom: "No listing files are generated [by the assembler]. Producing full listings may be a waste of effort because wdis (the Open Watcom disassembler) does a very good job. However, it could be extremely helpful to produce a dump of the internal symbol table the way MASM does, especially for diagnostic purposes."

[8] Open Watcom website: Disassembler Archived 2006-07-15 at the Wayback Machine

[9] The 1996 "WALK32 consists of the following main components:
A full-featured PE (Portable Executable) file linker called W32Link.

A main include file, containing Win32 constant, type, and structure definitions.

Another include file, containing the application and DLL startup source code.

Segment and PE section management macros.

Macros related to Unicode support.

Several demo applications and DLL’s.

A collection of programming utilities for various purposes." walk32.doc in walk32_1.zip

[10] A full-featured PE (Portable Executable) file linker called W32Link.

[11] A main include file, containing Win32 constant, type, and structure definitions.

[12] Another include file, containing the application and DLL startup source code.

[13] Segment and PE section management macros.

[14] Macros related to Unicode support.

[15] Several demo applications and DLL’s.

[16] A collection of programming utilities for various purposes." walk32.doc in walk32_1.zip

[10] GitHub/Baron-von-Riedesel/JWasm

[11] UASM Assembler Development

[12] HJWasm Releases

[13] A New Name? (thread page 1)

[14] A New Name? (thread page 3)

[15] UASM (2.33)

[16] UASM 2.33 Release

[17] UASM ChangeLog

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v t e x86 assembly topics
Topics	Assembly language Comparison of assemblers Disassembler Instruction set Low-level programming language Machine code Microassembler x86 assembly language
Assemblers	A86/A386 Flat Assembler (FASM) GNU Assembler (GAS) High Level Assembly (HLA) Microsoft Macro Assembler (MASM) Netwide Assembler (NASM) Turbo Assembler (TASM) Open Watcom Assembler (WASM)
Programming issues	Call stack Flags Carry flag Direction flag Interrupt flag Overflow flag Zero flag Memory address Opcode Program counter Processor register Calling conventions Instruction listings Registers