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# MMX 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 value in signed 16-bit input samples
# int peakval_mmx(signed short *in,int cnt);
.global peakval_mmx
.type peakval_mmx,@function
.align 16
peakval_mmx:
pushl %ebp
movl %esp,%ebp
pushl %esi
pushl %ecx
pushl %ebx
movl 8(%ebp),%esi
movl 12(%ebp),%ecx
pxor %mm7,%mm7 # clear peak
1: subl $4,%ecx
jl 2f
movq (%esi),%mm0
movq %mm0,%mm1
psraw $15,%mm1 # mm1 = 1's if negative, 0's if positive
pxor %mm1,%mm0 # complement negatives
psubw %mm1,%mm0 # add 1 to negatives
movq %mm7,%mm6 # copy previous peak
pcmpgtw %mm0,%mm6 # ff == old peak greater
pand %mm6,%mm7 # select old peaks that are greater
pandn %mm0,%mm6 # select new values that are greater
por %mm6,%mm7
addl $8,%esi
jmp 1b
2: movd %mm7,%eax
psrlq $16,%mm7
andl $0xffff,%eax
movd %mm7,%edx
psrlq $16,%mm7
andl $0xffff,%edx
cmpl %edx,%eax
jnl 3f
movl %edx,%eax
3:
movd %mm7,%edx
psrlq $16,%mm7
andl $0xffff,%edx
cmpl %edx,%eax
jnl 4f
movl %edx,%eax
4:
movd %mm7,%edx
andl $0xffff,%edx
cmpl %edx,%eax
jnl 5f
movl %edx,%eax
5:
emms
popl %ebx
popl %ecx
popl %esi
popl %ebp
ret
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