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@
@ Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
@
@ Use of this source code is governed by a BSD-style license
@ that can be found in the LICENSE file in the root of the source
@ tree. An additional intellectual property rights grant can be found
@ in the file PATENTS. All contributing project authors may
@ be found in the AUTHORS file in the root of the source tree.
@
@ This file contains the function WebRtcSpl_FilterARFastQ12(), optimized for
@ ARMv7 platform. The description header can be found in
@ signal_processing_library.h
@
@ Output is bit-exact with the generic C code as in filter_ar_fast_q12.c, and
@ the reference C code at end of this file.
@ Assumptions:
@ (1) data_length > 0
@ (2) coefficients_length > 1
@ Register usage:
@
@ r0: &data_in[i]
@ r1: &data_out[i], for result ouput
@ r2: &coefficients[0]
@ r3: coefficients_length
@ r4: Iteration counter for the outer loop.
@ r5: data_out[j] as multiplication inputs
@ r6: Calculated value for output data_out[]; interation counter for inner loop
@ r7: Partial sum of a filtering multiplication results
@ r8: Partial sum of a filtering multiplication results
@ r9: &data_out[], for filtering input; data_in[i]
@ r10: coefficients[j]
@ r11: Scratch
@ r12: &coefficients[j]
#include "rtc_base/system/asm_defines.h"
GLOBAL_FUNCTION WebRtcSpl_FilterARFastQ12
.align 2
DEFINE_FUNCTION WebRtcSpl_FilterARFastQ12
push {r4-r11}
ldrsh r12, [sp, #32] @ data_length
subs r4, r12, #1
beq ODD_LENGTH @ jump if data_length == 1
LOOP_LENGTH:
add r12, r2, r3, lsl #1
sub r12, #4 @ &coefficients[coefficients_length - 2]
sub r9, r1, r3, lsl #1
add r9, #2 @ &data_out[i - coefficients_length + 1]
ldr r5, [r9], #4 @ data_out[i - coefficients_length + {1,2}]
mov r7, #0 @ sum1
mov r8, #0 @ sum2
subs r6, r3, #3 @ Iteration counter for inner loop.
beq ODD_A_LENGTH @ branch if coefficients_length == 3
blt POST_LOOP_A_LENGTH @ branch if coefficients_length == 2
LOOP_A_LENGTH:
ldr r10, [r12], #-4 @ coefficients[j - 1], coefficients[j]
subs r6, #2
smlatt r8, r10, r5, r8 @ sum2 += coefficients[j] * data_out[i - j + 1];
smlatb r7, r10, r5, r7 @ sum1 += coefficients[j] * data_out[i - j];
smlabt r7, r10, r5, r7 @ coefficients[j - 1] * data_out[i - j + 1];
ldr r5, [r9], #4 @ data_out[i - j + 2], data_out[i - j + 3]
smlabb r8, r10, r5, r8 @ coefficients[j - 1] * data_out[i - j + 2];
bgt LOOP_A_LENGTH
blt POST_LOOP_A_LENGTH
ODD_A_LENGTH:
ldrsh r10, [r12, #2] @ Filter coefficients coefficients[2]
sub r12, #2 @ &coefficients[0]
smlabb r7, r10, r5, r7 @ sum1 += coefficients[2] * data_out[i - 2];
smlabt r8, r10, r5, r8 @ sum2 += coefficients[2] * data_out[i - 1];
ldr r5, [r9, #-2] @ data_out[i - 1], data_out[i]
POST_LOOP_A_LENGTH:
ldr r10, [r12] @ coefficients[0], coefficients[1]
smlatb r7, r10, r5, r7 @ sum1 += coefficients[1] * data_out[i - 1];
ldr r9, [r0], #4 @ data_in[i], data_in[i + 1]
smulbb r6, r10, r9 @ output1 = coefficients[0] * data_in[i];
sub r6, r7 @ output1 -= sum1;
sbfx r11, r6, #12, #16
ssat r7, #16, r6, asr #12
cmp r7, r11
addeq r6, r6, #2048
ssat r6, #16, r6, asr #12
strh r6, [r1], #2 @ Store data_out[i]
smlatb r8, r10, r6, r8 @ sum2 += coefficients[1] * data_out[i];
smulbt r6, r10, r9 @ output2 = coefficients[0] * data_in[i + 1];
sub r6, r8 @ output1 -= sum1;
sbfx r11, r6, #12, #16
ssat r7, #16, r6, asr #12
cmp r7, r11
addeq r6, r6, #2048
ssat r6, #16, r6, asr #12
strh r6, [r1], #2 @ Store data_out[i + 1]
subs r4, #2
bgt LOOP_LENGTH
blt END @ For even data_length, it's done. Jump to END.
@ Process i = data_length -1, for the case of an odd length.
ODD_LENGTH:
add r12, r2, r3, lsl #1
sub r12, #4 @ &coefficients[coefficients_length - 2]
sub r9, r1, r3, lsl #1
add r9, #2 @ &data_out[i - coefficients_length + 1]
mov r7, #0 @ sum1
mov r8, #0 @ sum1
subs r6, r3, #2 @ inner loop counter
beq EVEN_A_LENGTH @ branch if coefficients_length == 2
LOOP2_A_LENGTH:
ldr r10, [r12], #-4 @ coefficients[j - 1], coefficients[j]
ldr r5, [r9], #4 @ data_out[i - j], data_out[i - j + 1]
subs r6, #2
smlatb r7, r10, r5, r7 @ sum1 += coefficients[j] * data_out[i - j];
smlabt r8, r10, r5, r8 @ coefficients[j - 1] * data_out[i - j + 1];
bgt LOOP2_A_LENGTH
addlt r12, #2
blt POST_LOOP2_A_LENGTH
EVEN_A_LENGTH:
ldrsh r10, [r12, #2] @ Filter coefficients coefficients[1]
ldrsh r5, [r9] @ data_out[i - 1]
smlabb r7, r10, r5, r7 @ sum1 += coefficients[1] * data_out[i - 1];
POST_LOOP2_A_LENGTH:
ldrsh r10, [r12] @ Filter coefficients coefficients[0]
ldrsh r9, [r0] @ data_in[i]
smulbb r6, r10, r9 @ output1 = coefficients[0] * data_in[i];
sub r6, r7 @ output1 -= sum1;
sub r6, r8 @ output1 -= sum1;
sbfx r8, r6, #12, #16
ssat r7, #16, r6, asr #12
cmp r7, r8
addeq r6, r6, #2048
ssat r6, #16, r6, asr #12
strh r6, [r1] @ Store the data_out[i]
END:
pop {r4-r11}
bx lr
@Reference C code:
@
@void WebRtcSpl_FilterARFastQ12(int16_t* data_in,
@ int16_t* data_out,
@ int16_t* __restrict coefficients,
@ size_t coefficients_length,
@ size_t data_length) {
@ size_t i = 0;
@ size_t j = 0;
@
@ assert(data_length > 0);
@ assert(coefficients_length > 1);
@
@ for (i = 0; i < data_length - 1; i += 2) {
@ int32_t output1 = 0;
@ int32_t sum1 = 0;
@ int32_t output2 = 0;
@ int32_t sum2 = 0;
@
@ for (j = coefficients_length - 1; j > 2; j -= 2) {
@ sum1 += coefficients[j] * data_out[i - j];
@ sum1 += coefficients[j - 1] * data_out[i - j + 1];
@ sum2 += coefficients[j] * data_out[i - j + 1];
@ sum2 += coefficients[j - 1] * data_out[i - j + 2];
@ }
@
@ if (j == 2) {
@ sum1 += coefficients[2] * data_out[i - 2];
@ sum2 += coefficients[2] * data_out[i - 1];
@ }
@
@ sum1 += coefficients[1] * data_out[i - 1];
@ output1 = coefficients[0] * data_in[i];
@ output1 -= sum1;
@ // Saturate and store the output.
@ output1 = WEBRTC_SPL_SAT(134215679, output1, -134217728);
@ data_out[i] = (int16_t)((output1 + 2048) >> 12);
@
@ sum2 += coefficients[1] * data_out[i];
@ output2 = coefficients[0] * data_in[i + 1];
@ output2 -= sum2;
@ // Saturate and store the output.
@ output2 = WEBRTC_SPL_SAT(134215679, output2, -134217728);
@ data_out[i + 1] = (int16_t)((output2 + 2048) >> 12);
@ }
@
@ if (i == data_length - 1) {
@ int32_t output1 = 0;
@ int32_t sum1 = 0;
@
@ for (j = coefficients_length - 1; j > 1; j -= 2) {
@ sum1 += coefficients[j] * data_out[i - j];
@ sum1 += coefficients[j - 1] * data_out[i - j + 1];
@ }
@
@ if (j == 1) {
@ sum1 += coefficients[1] * data_out[i - 1];
@ }
@
@ output1 = coefficients[0] * data_in[i];
@ output1 -= sum1;
@ // Saturate and store the output.
@ output1 = WEBRTC_SPL_SAT(134215679, output1, -134217728);
@ data_out[i] = (int16_t)((output1 + 2048) >> 12);
@ }
@}