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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
|
|
