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

References

1. Randall Hyde. "WASM: The Open Watcom Assembler". Archived from the original on 2012-03-02. Retrieved 2017-09-11.
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
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. 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

External links

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