Apply my old patch from 2012 for x86_64

1 files changed, 254 insertions, 0 deletions

diff --git a/sse2bfly29-64.s b/sse2bfly29-64.s
new file mode 100644
index 0000000..22bd8a1
--- /dev/null
+++ b/sse2bfly29-64.s
@@ -0,0 +1,254 @@
+/* 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)
+
+   Modifications for x86_64, 2012 Matthias P. Braendli, HB9EGM
+   - changed registers to x86-64 equivalents
+   - changed instructions accordingly
+   - %rip indirect addressing needed for position independent code,
+     which is required because x86-64 needs dynamic libs to be PIC.
+     That still doesn't work
+
+   void update_viterbi29_blk_sse2(struct v29 *vp,unsigned char *syms,int nbits) ; 
+*/
+	# SSE2 (128-bit integer SIMD) version
+    # All X86-64 CPUs include SSE2
+
+	# These are offsets into struct v29, defined in viterbi29_av.c
+	.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:
+	pushq %rbp
+	movq %rsp,%rbp
+    /* convention different between i386 and x86_64: rsi and rdi belong to called function, not caller */
+    /* Let's say we don't care (yet) */
+	pushq %rsi
+	pushq %rdi
+	pushq %rdx
+	pushq %rbx
+	
+	movq 8(%rbp),%rdx	# edx = vp
+	testq %rdx,%rdx
+	jnz  0f
+	movq -1,%rax
+	jmp  err		
+0:	movq OLDMETRICS(%rdx),%rsi	# esi -> old metrics
+	movq NEWMETRICS(%rdx),%rdi	# edi -> new metrics
+	movq DP(%rdx),%rdx	# edx -> decisions
+
+1:	movq 16(%rbp),%rax	# eax = nbits
+	decq %rax
+	jl   2f			# passed zero, we're done
+	movq %rax,16(%rbp)
+
+	xorq %rax,%rax
+	movq 12(%rbp),%rbx	# ebx = syms
+	movb (%rbx),%al
+	movd %rax,%xmm6		# xmm6[0] = first symbol
+	movb 1(%rbx),%al
+	movd %rax,%xmm5		# xmm5[0] = second symbol
+	addq $2,%rbx
+	movq %rbx,12(%rbp)
+
+	punpcklbw %xmm6,%xmm6	# xmm6[1] = xmm6[0]
+	punpcklbw %xmm5,%xmm5
+	movdqa thirtyones(%rip),%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(%rip),%xmm7
+	
+	# each invocation of this macro does 16 butterflies in parallel
+	.MACRO butterfly GROUP
+	# compute branch metrics
+	movdqa Branchtab29_sse2+(16*\GROUP)(%rip),%xmm4
+	movdqa Branchtab29_sse2+128+(16*\GROUP)(%rip),%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)(%rdi)
+	movdqa %xmm4,(32*\GROUP)(%rdi)
+
+	# 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
+	shlq $16,%rbx
+	.byte 0x66,0x0f,0xd7,0xc4	# pmovmskb %xmm4,%eax
+	orq %rax,%rbx
+	movq %rbx,(4*\GROUP)(%rdx)
+	.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
+
+	addq $32,%rdx		# bump decision pointer
+		
+	# see if we have to normalize
+	movq (%rdi),%rax	# extract first output metric
+	andq $255,%rax
+	cmp $50,%rax		# is it greater than 50?
+	movq $0,%rax
+	jle done		# No, no need to normalize
+
+	# Normalize by finding smallest metric and subtracting it
+	# from all metrics
+	movdqa (%rdi),%xmm0
+	pminub 16(%rdi),%xmm0
+	pminub 32(%rdi),%xmm0
+	pminub 48(%rdi),%xmm0
+	pminub 64(%rdi),%xmm0
+	pminub 80(%rdi),%xmm0
+	pminub 96(%rdi),%xmm0	
+	pminub 112(%rdi),%xmm0	
+	pminub 128(%rdi),%xmm0
+	pminub 144(%rdi),%xmm0
+	pminub 160(%rdi),%xmm0
+	pminub 176(%rdi),%xmm0
+	pminub 192(%rdi),%xmm0
+	pminub 208(%rdi),%xmm0
+	pminub 224(%rdi),%xmm0
+	pminub 240(%rdi),%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 (%rdi),%xmm1
+	psubusb %xmm0,%xmm1
+	movdqa %xmm1,(%rdi)
+	movdqa 16(%rdi),%xmm1
+	psubusb %xmm0,%xmm1
+	movdqa %xmm1,16(%rdi)	
+	movdqa 32(%rdi),%xmm1
+	psubusb %xmm0,%xmm1	
+	movdqa %xmm1,32(%rdi)	
+	movdqa 48(%rdi),%xmm1
+	psubusb %xmm0,%xmm1	
+	movdqa %xmm1,48(%rdi)	
+	movdqa 64(%rdi),%xmm1
+	psubusb %xmm0,%xmm1	
+	movdqa %xmm1,64(%rdi)	
+	movdqa 80(%rdi),%xmm1
+	psubusb %xmm0,%xmm1	
+	movdqa %xmm1,80(%rdi)	
+	movdqa 96(%rdi),%xmm1	
+	psubusb %xmm0,%xmm1	
+	movdqa %xmm1,96(%rdi)	
+	movdqa 112(%rdi),%xmm1	
+	psubusb %xmm0,%xmm1	
+	movdqa %xmm1,112(%rdi)	
+	movdqa 128(%rdi),%xmm1
+	psubusb %xmm0,%xmm1	
+	movdqa %xmm1,128(%rdi)	
+	movdqa 144(%rdi),%xmm1
+	psubusb %xmm0,%xmm1	
+	movdqa %xmm1,144(%rdi)	
+	movdqa 160(%rdi),%xmm1
+	psubusb %xmm0,%xmm1	
+	movdqa %xmm1,160(%rdi)	
+	movdqa 176(%rdi),%xmm1
+	psubusb %xmm0,%xmm1
+	movdqa %xmm1,176(%rdi)	
+	movdqa 192(%rdi),%xmm1
+	psubusb %xmm0,%xmm1	
+	movdqa %xmm1,192(%rdi)	
+	movdqa 208(%rdi),%xmm1
+	psubusb %xmm0,%xmm1
+	movdqa %xmm1,208(%rdi)	
+	movdqa 224(%rdi),%xmm1
+	psubusb %xmm0,%xmm1	
+	movdqa %xmm1,224(%rdi)	
+	movdqa 240(%rdi),%xmm1							
+	psubusb %xmm0,%xmm1	
+	movdqa %xmm1,240(%rdi)	
+	
+done:		
+	# swap metrics
+	movq %rsi,%rax
+	movq %rdi,%rsi
+	movq %rax,%rdi
+	jmp 1b
+	
+2:	movq 8(%rbp),%rbx	# ebx = vp
+	# stash metric pointers
+	movq %rsi,OLDMETRICS(%rbx)
+	movq %rdi,NEWMETRICS(%rbx)
+	movq %rdx,DP(%rbx)	# stash incremented value of vp->dp
+	xorq %rax,%rax
+err:	popq %rbx
+	popq %rdx
+	popq %rdi
+	popq %rsi
+	popq %rbp
+	ret
+	
+	.data
+	.align 16
+thirtyones:	
+	.byte 31,31,31,31,31,31,31,31,31,31,31,31,31,31,31,31
+