| Bill Yi | 4e213d5 | 2015-06-23 13:53:11 -0700 | [diff] [blame] | 1 | # MMX assist routines for peakval |
| 2 | # Copyright 2001 Phil Karn, KA9Q |
| 3 | # May be used under the terms of the GNU Lesser General Public License (LGPL) |
| 4 | |
| 5 | .text |
| 6 | |
| 7 | # Find peak value in signed 16-bit input samples |
| 8 | # int peakval_mmx(signed short *in,int cnt); |
| 9 | .global peakval_mmx |
| 10 | .type peakval_mmx,@function |
| 11 | .align 16 |
| 12 | peakval_mmx: |
| 13 | pushl %ebp |
| 14 | movl %esp,%ebp |
| 15 | pushl %esi |
| 16 | pushl %ecx |
| 17 | pushl %ebx |
| 18 | |
| 19 | movl 8(%ebp),%esi |
| 20 | movl 12(%ebp),%ecx |
| 21 | |
| 22 | pxor %mm7,%mm7 # clear peak |
| 23 | |
| 24 | 1: subl $4,%ecx |
| 25 | jl 2f |
| 26 | movq (%esi),%mm0 |
| 27 | movq %mm0,%mm1 |
| 28 | psraw $15,%mm1 # mm1 = 1's if negative, 0's if positive |
| 29 | pxor %mm1,%mm0 # complement negatives |
| 30 | psubw %mm1,%mm0 # add 1 to negatives |
| 31 | movq %mm7,%mm6 # copy previous peak |
| 32 | pcmpgtw %mm0,%mm6 # ff == old peak greater |
| 33 | pand %mm6,%mm7 # select old peaks that are greater |
| 34 | pandn %mm0,%mm6 # select new values that are greater |
| 35 | por %mm6,%mm7 |
| 36 | |
| 37 | addl $8,%esi |
| 38 | jmp 1b |
| 39 | |
| 40 | 2: movd %mm7,%eax |
| 41 | psrlq $16,%mm7 |
| 42 | andl $0xffff,%eax |
| 43 | |
| 44 | movd %mm7,%edx |
| 45 | psrlq $16,%mm7 |
| 46 | andl $0xffff,%edx |
| 47 | cmpl %edx,%eax |
| 48 | jnl 3f |
| 49 | movl %edx,%eax |
| 50 | 3: |
| 51 | movd %mm7,%edx |
| 52 | psrlq $16,%mm7 |
| 53 | andl $0xffff,%edx |
| 54 | cmpl %edx,%eax |
| 55 | jnl 4f |
| 56 | movl %edx,%eax |
| 57 | 4: |
| 58 | movd %mm7,%edx |
| 59 | andl $0xffff,%edx |
| 60 | cmpl %edx,%eax |
| 61 | jnl 5f |
| 62 | movl %edx,%eax |
| 63 | 5: |
| 64 | emms |
| 65 | popl %ebx |
| 66 | popl %ecx |
| 67 | popl %esi |
| 68 | popl %ebp |
| 69 | ret |
| 70 | |