I want to add some assembly code asm to the project. I modified Makefile.am and added source+=xx.asm did not take effect. Do I need to modify configure.ac or other files?

[Dongbo Liu]

I want to add some assembly code asm to the project. I modified Makefile.am and added source+=xx.asm did not take effect. Do I need to modify configure.ac or other files?

[James Zern]

Hi,

On Thu, May 25, 2023 at 8:42 PM 'Dongbo Liu' via WebP Discussion <webp-d...@webmproject.org> wrote:

I want to add some assembly code asm to the project. I modified Makefile.am and added source+=xx.asm did not take effect. Do I need to modify configure.ac or other files?

In general for this project we prefer using compiler intrinsics, for local testing you can add AM_PROG_AS to configure.ac and rerun ./autogen.sh. You may need to use .s as the file extension to satisfy the default suffix rules.

[Dongbo Liu]

I add AM_PROG_AS to configure.ac and rerun ./autogen.sh. but it dosen't work,  can you show me full code for this? i use nasm to compile .s，like nasm -f elf64 scan.s

[Dongbo Liu]

some error

scanLast.s: Assembler messages:
scanLast.s:1: Error: no such instruction: `uint16_t scanLast(uint16_t* coeffs)'
scanLast.s:2: Error: no such instruction: `global scanLast_test'
scanLast.s:3: Error: no such instruction: `global bswap'
scanLast.s:4: Error: no such instruction: `global scanLast'
scanLast.s:6: Error: invalid char '[' beginning operand 2 `[rdi]'
scanLast.s:7: Error: too many memory references for `vpxord'
scanLast.s:8: Error: too many memory references for `vpabsw'
scanLast.s:9: Error: too many memory references for `vpcmpw'
scanLast.s:10: Error: too many memory references for `kmovw'
scanLast.s:11: Error: no instruction mnemonic suffix given and no register operands; can't size instruction
scanLast.s:14: Error: too many memory references for `mov'
scanLast.s:15: Error: operand size mismatch for `bswap'

[Dongbo Liu]

my .s code

;uint16_t scanLast(uint16_t* coeffs);//return cmp with 0 mask

global scanLast_test

global bswap

global scanLast

scanLast:

vmovdqu ymm0, [rdi]

vpxord ymm1, ymm1

vpabsw ymm3, ymm0

vpcmpw k1, ymm1, ymm3, 01b

kmovw eax, k1

;not eax

ret

bswap:

mov rax, rdi

bswap rax

ret

[James Zern]

.s usually means assembly in GAS syntax. nasm or yasm will require more work in Makefile.am. mozjpeg had some rules for .asm files before switching to CMake:
https://github.com/mozilla/mozjpeg/blob/f34f2f5bc63633d385b22bb33388d55d5b1b8c37/simd/Makefile.am#L117