diff options
Diffstat (limited to 'src/common_audio/signal_processing/spl_sqrt_floor.c')
| -rw-r--r-- | src/common_audio/signal_processing/spl_sqrt_floor.c | 67 |
1 files changed, 34 insertions, 33 deletions
diff --git a/src/common_audio/signal_processing/spl_sqrt_floor.c b/src/common_audio/signal_processing/spl_sqrt_floor.c index aa36459ec4..62041b3dc8 100644 --- a/src/common_audio/signal_processing/spl_sqrt_floor.c +++ b/src/common_audio/signal_processing/spl_sqrt_floor.c @@ -1,21 +1,26 @@ /* - * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. + * Written by Wilco Dijkstra, 1996. + * Refer to NOTICE file at the root of git project. * - * 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. + * Minor modifications in code style for WebRTC, 2012. */ +#include "signal_processing_library.h" + /* - * This file contains the function WebRtcSpl_SqrtFloor(). - * The description header can be found in signal_processing_library.h + * Algorithm: + * Successive approximation of the equation (root + delta) ^ 2 = N + * until delta < 1. If delta < 1 we have the integer part of SQRT (N). + * Use delta = 2^i for i = 15 .. 0. + * + * Output precision is 16 bits. Note for large input values (close to + * 0x7FFFFFFF), bit 15 (the highest bit of the low 16-bit half word) + * contains the MSB information (a non-sign value). Do with caution + * if you need to cast the output to int16_t type. * + * If the input value is negative, it returns 0. */ -#include "signal_processing_library.h" - #define WEBRTC_SPL_SQRT_ITER(N) \ try1 = root + (1 << (N)); \ if (value >= try1 << (N)) \ @@ -24,30 +29,26 @@ root |= 2 << (N); \ } -// (out) Square root of input parameter -WebRtc_Word32 WebRtcSpl_SqrtFloor(WebRtc_Word32 value) +int32_t WebRtcSpl_SqrtFloor(int32_t value) { - // new routine for performance, 4 cycles/bit in ARM - // output precision is 16 bits - - WebRtc_Word32 root = 0, try1; + int32_t root = 0, try1; - WEBRTC_SPL_SQRT_ITER (15); - WEBRTC_SPL_SQRT_ITER (14); - WEBRTC_SPL_SQRT_ITER (13); - WEBRTC_SPL_SQRT_ITER (12); - WEBRTC_SPL_SQRT_ITER (11); - WEBRTC_SPL_SQRT_ITER (10); - WEBRTC_SPL_SQRT_ITER ( 9); - WEBRTC_SPL_SQRT_ITER ( 8); - WEBRTC_SPL_SQRT_ITER ( 7); - WEBRTC_SPL_SQRT_ITER ( 6); - WEBRTC_SPL_SQRT_ITER ( 5); - WEBRTC_SPL_SQRT_ITER ( 4); - WEBRTC_SPL_SQRT_ITER ( 3); - WEBRTC_SPL_SQRT_ITER ( 2); - WEBRTC_SPL_SQRT_ITER ( 1); - WEBRTC_SPL_SQRT_ITER ( 0); + WEBRTC_SPL_SQRT_ITER (15); + WEBRTC_SPL_SQRT_ITER (14); + WEBRTC_SPL_SQRT_ITER (13); + WEBRTC_SPL_SQRT_ITER (12); + WEBRTC_SPL_SQRT_ITER (11); + WEBRTC_SPL_SQRT_ITER (10); + WEBRTC_SPL_SQRT_ITER ( 9); + WEBRTC_SPL_SQRT_ITER ( 8); + WEBRTC_SPL_SQRT_ITER ( 7); + WEBRTC_SPL_SQRT_ITER ( 6); + WEBRTC_SPL_SQRT_ITER ( 5); + WEBRTC_SPL_SQRT_ITER ( 4); + WEBRTC_SPL_SQRT_ITER ( 3); + WEBRTC_SPL_SQRT_ITER ( 2); + WEBRTC_SPL_SQRT_ITER ( 1); + WEBRTC_SPL_SQRT_ITER ( 0); - return root >> 1; + return root >> 1; } |