1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
|
# SSE2 assist routines for peakval
# Copyright 2001 Phil Karn, KA9Q
# May be used under the terms of the GNU Public License (GPL)
.text
# Find peak absolute value in signed 16-bit input samples
# int peakval_sse2(signed short *in,int cnt);
.global peakval_sse2
.type peakval_sse2,@function
.align 16
peakval_sse2:
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
|
