diff options
Diffstat (limited to 'sse2bfly29.s')
| -rw-r--r-- | sse2bfly29.s | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/sse2bfly29.s b/sse2bfly29.s new file mode 100644 index 0000000..0fa1742 --- /dev/null +++ b/sse2bfly29.s @@ -0,0 +1,245 @@ +/* Intel SIMD SSE2 implementation of Viterbi ACS butterflies + for 256-state (k=9) convolutional code + Copyright 2004 Phil Karn, KA9Q + This code may be used under the terms of the GNU Lesser General Public License (LGPL) + + void update_viterbi29_blk_sse2(struct v29 *vp,unsigned char *syms,int nbits) ; +*/ + + # SSE2 (128-bit integer SIMD) version + # Requires Pentium 4 or better + # These are offsets into struct v29, defined in viterbi29.h + .set DP,512 + .set OLDMETRICS,516 + .set NEWMETRICS,520 + + .text + .global update_viterbi29_blk_sse2,Branchtab29_sse2 + .type update_viterbi29_blk_sse2,@function + .align 16 + +update_viterbi29_blk_sse2: + pushl %ebp + movl %esp,%ebp + pushl %esi + pushl %edi + pushl %edx + pushl %ebx + + movl 8(%ebp),%edx # edx = vp + testl %edx,%edx + jnz 0f + movl -1,%eax + jmp err +0: movl OLDMETRICS(%edx),%esi # esi -> old metrics + movl NEWMETRICS(%edx),%edi # edi -> new metrics + movl DP(%edx),%edx # edx -> decisions + +1: movl 16(%ebp),%eax # eax = nbits + decl %eax + jl 2f # passed zero, we're done + movl %eax,16(%ebp) + + xorl %eax,%eax + movl 12(%ebp),%ebx # ebx = syms + movb (%ebx),%al + movd %eax,%xmm6 # xmm6[0] = first symbol + movb 1(%ebx),%al + movd %eax,%xmm5 # xmm5[0] = second symbol + addl $2,%ebx + movl %ebx,12(%ebp) + + punpcklbw %xmm6,%xmm6 # xmm6[1] = xmm6[0] + punpcklbw %xmm5,%xmm5 + movdqa thirtyones,%xmm7 + pshuflw $0,%xmm6,%xmm6 # copy low word to low 3 + pshuflw $0,%xmm5,%xmm5 + punpcklqdq %xmm6,%xmm6 # propagate to all 16 + punpcklqdq %xmm5,%xmm5 + # xmm6 now contains first symbol in each byte, xmm5 the second + + movdqa thirtyones,%xmm7 + + # each invocation of this macro does 16 butterflies in parallel + .MACRO butterfly GROUP + # compute branch metrics + movdqa Branchtab29_sse2+(16*\GROUP),%xmm4 + movdqa Branchtab29_sse2+128+(16*\GROUP),%xmm3 + pxor %xmm6,%xmm4 + pxor %xmm5,%xmm3 + pavgb %xmm3,%xmm4 + psrlw $3,%xmm4 + + pand %xmm7,%xmm4 # xmm4 contains branch metrics + + movdqa (16*\GROUP)(%esi),%xmm0 # Incoming path metric, high bit = 0 + movdqa ((16*\GROUP)+128)(%esi),%xmm3 # Incoming path metric, high bit = 1 + movdqa %xmm0,%xmm2 + movdqa %xmm3,%xmm1 + paddusb %xmm4,%xmm0 + paddusb %xmm4,%xmm3 + + # invert branch metrics + pxor %xmm7,%xmm4 + + paddusb %xmm4,%xmm1 + paddusb %xmm4,%xmm2 + + # Find survivors, leave in mm0,2 + pminub %xmm1,%xmm0 + pminub %xmm3,%xmm2 + # get decisions, leave in mm1,3 + pcmpeqb %xmm0,%xmm1 + pcmpeqb %xmm2,%xmm3 + + # interleave and store new branch metrics in mm0,2 + movdqa %xmm0,%xmm4 + punpckhbw %xmm2,%xmm0 # interleave second 16 new metrics + punpcklbw %xmm2,%xmm4 # interleave first 16 new metrics + movdqa %xmm0,(32*\GROUP+16)(%edi) + movdqa %xmm4,(32*\GROUP)(%edi) + + # interleave decisions & store + movdqa %xmm1,%xmm4 + punpckhbw %xmm3,%xmm1 + punpcklbw %xmm3,%xmm4 + # work around bug in gas due to Intel doc error + .byte 0x66,0x0f,0xd7,0xd9 # pmovmskb %xmm1,%ebx + shll $16,%ebx + .byte 0x66,0x0f,0xd7,0xc4 # pmovmskb %xmm4,%eax + orl %eax,%ebx + movl %ebx,(4*\GROUP)(%edx) + .endm + + # invoke macro 8 times for a total of 128 butterflies + butterfly GROUP=0 + butterfly GROUP=1 + butterfly GROUP=2 + butterfly GROUP=3 + butterfly GROUP=4 + butterfly GROUP=5 + butterfly GROUP=6 + butterfly GROUP=7 + + addl $32,%edx # bump decision pointer + + # see if we have to normalize + movl (%edi),%eax # extract first output metric + andl $255,%eax + cmp $50,%eax # is it greater than 50? + movl $0,%eax + jle done # No, no need to normalize + + # Normalize by finding smallest metric and subtracting it + # from all metrics + movdqa (%edi),%xmm0 + pminub 16(%edi),%xmm0 + pminub 32(%edi),%xmm0 + pminub 48(%edi),%xmm0 + pminub 64(%edi),%xmm0 + pminub 80(%edi),%xmm0 + pminub 96(%edi),%xmm0 + pminub 112(%edi),%xmm0 + pminub 128(%edi),%xmm0 + pminub 144(%edi),%xmm0 + pminub 160(%edi),%xmm0 + pminub 176(%edi),%xmm0 + pminub 192(%edi),%xmm0 + pminub 208(%edi),%xmm0 + pminub 224(%edi),%xmm0 + pminub 240(%edi),%xmm0 + + # crunch down to single lowest metric + movdqa %xmm0,%xmm1 + psrldq $8,%xmm0 # the count to psrldq is bytes, not bits! + pminub %xmm1,%xmm0 + movdqa %xmm0,%xmm1 + psrlq $32,%xmm0 + pminub %xmm1,%xmm0 + movdqa %xmm0,%xmm1 + psrlq $16,%xmm0 + pminub %xmm1,%xmm0 + movdqa %xmm0,%xmm1 + psrlq $8,%xmm0 + pminub %xmm1,%xmm0 + + punpcklbw %xmm0,%xmm0 # lowest 2 bytes + pshuflw $0,%xmm0,%xmm0 # lowest 8 bytes + punpcklqdq %xmm0,%xmm0 # all 16 bytes + + # xmm0 now contains lowest metric in all 16 bytes + # subtract it from every output metric + movdqa (%edi),%xmm1 + psubusb %xmm0,%xmm1 + movdqa %xmm1,(%edi) + movdqa 16(%edi),%xmm1 + psubusb %xmm0,%xmm1 + movdqa %xmm1,16(%edi) + movdqa 32(%edi),%xmm1 + psubusb %xmm0,%xmm1 + movdqa %xmm1,32(%edi) + movdqa 48(%edi),%xmm1 + psubusb %xmm0,%xmm1 + movdqa %xmm1,48(%edi) + movdqa 64(%edi),%xmm1 + psubusb %xmm0,%xmm1 + movdqa %xmm1,64(%edi) + movdqa 80(%edi),%xmm1 + psubusb %xmm0,%xmm1 + movdqa %xmm1,80(%edi) + movdqa 96(%edi),%xmm1 + psubusb %xmm0,%xmm1 + movdqa %xmm1,96(%edi) + movdqa 112(%edi),%xmm1 + psubusb %xmm0,%xmm1 + movdqa %xmm1,112(%edi) + movdqa 128(%edi),%xmm1 + psubusb %xmm0,%xmm1 + movdqa %xmm1,128(%edi) + movdqa 144(%edi),%xmm1 + psubusb %xmm0,%xmm1 + movdqa %xmm1,144(%edi) + movdqa 160(%edi),%xmm1 + psubusb %xmm0,%xmm1 + movdqa %xmm1,160(%edi) + movdqa 176(%edi),%xmm1 + psubusb %xmm0,%xmm1 + movdqa %xmm1,176(%edi) + movdqa 192(%edi),%xmm1 + psubusb %xmm0,%xmm1 + movdqa %xmm1,192(%edi) + movdqa 208(%edi),%xmm1 + psubusb %xmm0,%xmm1 + movdqa %xmm1,208(%edi) + movdqa 224(%edi),%xmm1 + psubusb %xmm0,%xmm1 + movdqa %xmm1,224(%edi) + movdqa 240(%edi),%xmm1 + psubusb %xmm0,%xmm1 + movdqa %xmm1,240(%edi) + +done: + # swap metrics + movl %esi,%eax + movl %edi,%esi + movl %eax,%edi + jmp 1b + +2: movl 8(%ebp),%ebx # ebx = vp + # stash metric pointers + movl %esi,OLDMETRICS(%ebx) + movl %edi,NEWMETRICS(%ebx) + movl %edx,DP(%ebx) # stash incremented value of vp->dp + xorl %eax,%eax +err: popl %ebx + popl %edx + popl %edi + popl %esi + popl %ebp + ret + + .data + .align 16 +thirtyones: + .byte 31,31,31,31,31,31,31,31,31,31,31,31,31,31,31,31 + |