[fpc-devel] x86ins.dat

[Sergei Gorelkin]

07.01.2012 16:53, tgrundke пишет:
> Hi,
>
> i am working on the AVX-support for the fp-compiler.
>
> Some AVX-assembler instructions have 4 operant e.g.
>
>
> VBLENDVPD xmm1, xmm2, xmm3/m128, xmm4
>
>
>
> INTEL Def.
>
> 3.1.1.2 Opcode Column in the Instruction Summary Table (Instructions
> with VEX prefix)
>
> /is4: An 8-bit immediate byte is present containing a source register specifier in
> imm[7:4] and instruction-specific payload in imm[3:0].
>
>
>
> I need a idea, how can i encode (in file x86ins.dat)  the 4th operant.
>
> My idea:
>
> new flag \77 =>> 4th operand is coded in bit 4-7 and the follow byte define the bits 0-3
> e.g.
>
> [VBLENDVPD]
> (Ch_All, Ch_None, Ch_None)
> xmmreg,xmmreg,xmmrm,xmmreg                  \361\362\372\1\x4B\75\120\77\x00
> AVX,SANDYBRIDGE
>
> \ 361 = prefix 066h for SSE instruction
> \ 362 = new flag VEX (starting with 0xC5 or 0xC4)
> \ 372 = new flag VEX-CODE include prefix 0x0F3A
> \ 75   = VEX-BYTE contains operand no. 2
> \ 120 = operands 1 and 3 encoded in MODRM-Byte
> \ 77   = immediate byte (bit 4-7) contains 4th operand
> \ 00   = immediate byte (bit 0-3) = 0
>
>
> i look forward to comments.
>
IMHO, since fpc's x86 assembler is based on NASM, the best way would be to stay as close to NASM 
format as possible.

Sergei