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 "webrtc/system_wrappers/include/asm_defines.h" 29 #include "settings.h" 30 31 GLOBAL_FUNCTION WebRtcIsacfix_FilterArLoop 32 .align 2 33 DEFINE_FUNCTION WebRtcIsacfix_FilterArLoop 34 push {r4-r11} 35 36 add r1, #2 @ &ar_f_Q0[1] 37 mov r12, #16384 38 mov r4, #HALF_SUBFRAMELEN 39 sub r4, #1 @ Outer loop counter = HALF_SUBFRAMELEN - 1 40 41 HALF_SUBFRAME_LOOP: @ for (n = 0; n < HALF_SUBFRAMELEN - 1; n++) 42 43 ldr r9, [sp, #32] @ Restore the inner loop counter to order_coef 44 ldrh r5, [r1] @ tmpAR = ar_f_Q0[n+1] 45 add r0, r9, asl #1 @ Restore r0 to &ar_g_Q0[order_coef] 46 add r2, r9, asl #1 @ Restore r2 to &cth_Q15[order_coef] 47 add r3, r9, asl #1 @ Restore r3 to &sth_Q15[order_coef] 48 49 ORDER_COEF_LOOP: @ for (k = order_coef; k > 0; k--) 50 51 ldrh r7, [r3, #-2]! @ sth_Q15[k - 1] 52 ldrh r6, [r2, #-2]! @ cth_Q15[k - 1] 53 54 ldrh r8, [r0, #-2] @ ar_g_Q0[k - 1] 55 smlabb r11, r7, r5, r12 @ sth_Q15[k - 1] * tmpAR + 16384 56 smlabb r10, r6, r5, r12 @ cth_Q15[k - 1] * tmpAR + 16384 57 smulbb r7, r7, r8 @ sth_Q15[k - 1] * ar_g_Q0[k - 1] 58 smlabb r11, r6, r8, r11 @ cth_Q15[k - 1] * ar_g_Q0[k - 1] + 59 @ (sth_Q15[k - 1] * tmpAR + 16384) 60 61 sub r10, r10, r7 @ cth_Q15[k - 1] * tmpAR + 16384 - 62 @ (sth_Q15[k - 1] * ar_g_Q0[k - 1]) 63 ssat r11, #16, r11, asr #15 64 ssat r5, #16, r10, asr #15 65 strh r11, [r0], #-2 @ Output: ar_g_Q0[k] 66 67 subs r9, #1 68 bgt ORDER_COEF_LOOP 69 70 strh r5, [r0] @ Output: ar_g_Q0[0] = tmpAR; 71 strh r5, [r1], #2 @ Output: ar_f_Q0[n+1] = tmpAR; 72 73 subs r4, #1 74 bne HALF_SUBFRAME_LOOP 75 76 pop {r4-r11} 77 bx lr 78
