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# SSE2 assist routines for peakval
# Copyright 2001 Phil Karn, KA9Q
# May be used under the terms of the GNU Lesser General Public License (LGPL)
.text
# Find peak absolute value in signed 16-bit input samples
# int peakval_sse2_assist(signed short *in,int cnt);
.global peakval_sse2_assist
.type peakval_sse2_assist,@function
.align 16
peakval_sse2_assist:
pushl %ebp
movl %esp,%ebp
pushl %esi
pushl %ecx
movl 8(%ebp),%esi
movl 12(%ebp),%ecx
pxor %xmm7,%xmm7 # clear peak
1: subl $8,%ecx
jl 2f
movaps (%esi),%xmm0
movaps %xmm0,%xmm1
psraw $15,%xmm1 # xmm1 = 1's if negative, 0's if positive
pxor %xmm1,%xmm0 # complement negatives
psubw %xmm1,%xmm0 # add 1 to negatives
pmaxsw %xmm0,%xmm7 # store peak
addl $16,%esi
jmp 1b
2: movaps %xmm7,%xmm0
psrldq $8,%xmm0
pmaxsw %xmm0,%xmm7
movaps %xmm7,%xmm0
psrlq $32,%xmm0
pmaxsw %xmm0,%xmm7
movaps %xmm7,%xmm0
psrlq $16,%xmm0
pmaxsw %xmm0,%xmm7 # min value in low word of %xmm7
movd %xmm7,%eax
andl $0xffff,%eax
popl %ecx
popl %esi
popl %ebp
ret
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