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Diffstat (limited to 'third_party/webrtc/src/webrtc/common_audio/signal_processing/division_operations.c')
-rw-r--r-- | third_party/webrtc/src/webrtc/common_audio/signal_processing/division_operations.c | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/third_party/webrtc/src/webrtc/common_audio/signal_processing/division_operations.c b/third_party/webrtc/src/webrtc/common_audio/signal_processing/division_operations.c new file mode 100644 index 00000000..eaa06a1f --- /dev/null +++ b/third_party/webrtc/src/webrtc/common_audio/signal_processing/division_operations.c @@ -0,0 +1,138 @@ +/* + * Copyright (c) 2011 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 implementations of the divisions + * WebRtcSpl_DivU32U16() + * WebRtcSpl_DivW32W16() + * WebRtcSpl_DivW32W16ResW16() + * WebRtcSpl_DivResultInQ31() + * WebRtcSpl_DivW32HiLow() + * + * The description header can be found in signal_processing_library.h + * + */ + +#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h" + +uint32_t WebRtcSpl_DivU32U16(uint32_t num, uint16_t den) +{ + // Guard against division with 0 + if (den != 0) + { + return (uint32_t)(num / den); + } else + { + return (uint32_t)0xFFFFFFFF; + } +} + +int32_t WebRtcSpl_DivW32W16(int32_t num, int16_t den) +{ + // Guard against division with 0 + if (den != 0) + { + return (int32_t)(num / den); + } else + { + return (int32_t)0x7FFFFFFF; + } +} + +int16_t WebRtcSpl_DivW32W16ResW16(int32_t num, int16_t den) +{ + // Guard against division with 0 + if (den != 0) + { + return (int16_t)(num / den); + } else + { + return (int16_t)0x7FFF; + } +} + +int32_t WebRtcSpl_DivResultInQ31(int32_t num, int32_t den) +{ + int32_t L_num = num; + int32_t L_den = den; + int32_t div = 0; + int k = 31; + int change_sign = 0; + + if (num == 0) + return 0; + + if (num < 0) + { + change_sign++; + L_num = -num; + } + if (den < 0) + { + change_sign++; + L_den = -den; + } + while (k--) + { + div <<= 1; + L_num <<= 1; + if (L_num >= L_den) + { + L_num -= L_den; + div++; + } + } + if (change_sign == 1) + { + div = -div; + } + return div; +} + +int32_t WebRtcSpl_DivW32HiLow(int32_t num, int16_t den_hi, int16_t den_low) +{ + int16_t approx, tmp_hi, tmp_low, num_hi, num_low; + int32_t tmpW32; + + approx = (int16_t)WebRtcSpl_DivW32W16((int32_t)0x1FFFFFFF, den_hi); + // result in Q14 (Note: 3FFFFFFF = 0.5 in Q30) + + // tmpW32 = 1/den = approx * (2.0 - den * approx) (in Q30) + tmpW32 = (den_hi * approx << 1) + ((den_low * approx >> 15) << 1); + // tmpW32 = den * approx + + tmpW32 = (int32_t)0x7fffffffL - tmpW32; // result in Q30 (tmpW32 = 2.0-(den*approx)) + + // Store tmpW32 in hi and low format + tmp_hi = (int16_t)(tmpW32 >> 16); + tmp_low = (int16_t)((tmpW32 - ((int32_t)tmp_hi << 16)) >> 1); + + // tmpW32 = 1/den in Q29 + tmpW32 = (tmp_hi * approx + (tmp_low * approx >> 15)) << 1; + + // 1/den in hi and low format + tmp_hi = (int16_t)(tmpW32 >> 16); + tmp_low = (int16_t)((tmpW32 - ((int32_t)tmp_hi << 16)) >> 1); + + // Store num in hi and low format + num_hi = (int16_t)(num >> 16); + num_low = (int16_t)((num - ((int32_t)num_hi << 16)) >> 1); + + // num * (1/den) by 32 bit multiplication (result in Q28) + + tmpW32 = num_hi * tmp_hi + (num_hi * tmp_low >> 15) + + (num_low * tmp_hi >> 15); + + // Put result in Q31 (convert from Q28) + tmpW32 = WEBRTC_SPL_LSHIFT_W32(tmpW32, 3); + + return tmpW32; +} |