1 @ 2 @ Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. 3 @ 4 @ Use of this source code is governed by a BSD-style license 5 @ that can be found in the LICENSE file in the root of the source 6 @ tree. An additional intellectual property rights grant can be found 7 @ in the file PATENTS. All contributing project authors may 8 @ be found in the AUTHORS file in the root of the source tree. 9 @ 10 11 @ Contains a function for the core loop in the normalized lattice AR 12 @ filter routine for iSAC codec, optimized for ARMv7 platforms. 13 @ 14 @ Output is bit-exact with the reference C code in lattic_c.c 15 @ 16 @ Register usage: 17 @ 18 @ r0: &ar_g_Q0 19 @ r1: &ar_f_Q0 20 @ r2: &cth_Q15 21 @ r3: &sth_Q15 22 @ r4: out loop counter 23 @ r5: tmpAR 24 @ r9: inner loop counter 25 @ r12: constant #16384 26 @ r6, r7, r8, r10, r11: scratch 27 28 #include "settings.h" 29 30 .arch armv7-a 31 .global WebRtcIsacfix_FilterArLoop 32 .align 2 33 34 WebRtcIsacfix_FilterArLoop: 35 .fnstart 36 37 .save {r4-r11} 38 push {r4-r11} 39 40 add r1, #2 @ &ar_f_Q0[1] 41 mov r12, #16384 42 mov r4, #HALF_SUBFRAMELEN 43 sub r4, #1 @ Outer loop counter = HALF_SUBFRAMELEN - 1 44 45 HALF_SUBFRAME_LOOP: @ for(n = 0; n < HALF_SUBFRAMELEN - 1; n++) 46 47 ldr r9, [sp, #32] @ Restore the inner loop counter to order_coef 48 ldrh r5, [r1] @ tmpAR = ar_f_Q0[n+1] 49 add r0, r9, asl #1 @ Restore r0 to &ar_g_Q0[order_coef] 50 add r2, r9, asl #1 @ Restore r2 to &cth_Q15[order_coef] 51 add r3, r9, asl #1 @ Restore r3 to &sth_Q15[order_coef] 52 53 ORDER_COEF_LOOP: @ for(k = order_coef - 1 ; k >= 0; k--) 54 55 ldrh r7, [r3, #-2]! @ sth_Q15[k] 56 ldrh r6, [r2, #-2]! @ cth_Q15[k] 57 58 ldrh r8, [r0, #-2] @ ar_g_Q0[k] 59 smlabb r11, r7, r5, r12 @ sth_Q15[k] * tmpAR + 16384 60 smlabb r10, r6, r5, r12 @ cth_Q15[k] * tmpAR + 16384 61 smulbb r7, r7, r8 @ sth_Q15[k] * ar_g_Q0[k] 62 smlabb r11, r6, r8, r11 @ cth_Q15[k]*ar_g_Q0[k]+(sth_Q15[k]*tmpAR+16384) 63 64 sub r10, r10, r7 @ cth_Q15[k]*tmpAR+16384-(sth_Q15[k]*ar_g_Q0[k]) 65 ssat r11, #16, r11, asr #15 66 ssat r5, #16, r10, asr #15 67 strh r11, [r0], #-2 @ Output: ar_g_Q0[k+1] 68 69 subs r9, #1 70 bgt ORDER_COEF_LOOP 71 72 strh r5, [r0] @ Output: ar_g_Q0[0] = tmpAR; 73 strh r5, [r1], #2 @ Output: ar_f_Q0[n+1] = tmpAR; 74 75 subs r4, #1 76 bne HALF_SUBFRAME_LOOP 77 78 pop {r4-r11} 79 bx lr 80 81 .fnend 82 83
