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60 lines
1.6 KiB
C
60 lines
1.6 KiB
C
/*
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* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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/*
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* This file contains the function WebRtcSpl_DownsampleFast().
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* The description header can be found in signal_processing_library.h
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*
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*/
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#include "signal_processing_library.h"
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int WebRtcSpl_DownsampleFast(WebRtc_Word16 *in_ptr, WebRtc_Word16 in_length,
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WebRtc_Word16 *out_ptr, WebRtc_Word16 out_length,
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WebRtc_Word16 *B, WebRtc_Word16 B_length, WebRtc_Word16 factor,
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WebRtc_Word16 delay)
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{
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WebRtc_Word32 o;
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int i, j;
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WebRtc_Word16 *downsampled_ptr = out_ptr;
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WebRtc_Word16 *b_ptr;
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WebRtc_Word16 *x_ptr;
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WebRtc_Word16 endpos = delay
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+ (WebRtc_Word16)WEBRTC_SPL_MUL_16_16(factor, (out_length - 1)) + 1;
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if (in_length < endpos)
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{
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return -1;
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}
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for (i = delay; i < endpos; i += factor)
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{
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b_ptr = &B[0];
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x_ptr = &in_ptr[i];
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o = (WebRtc_Word32)2048; // Round val
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for (j = 0; j < B_length; j++)
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{
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o += WEBRTC_SPL_MUL_16_16(*b_ptr++, *x_ptr--);
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}
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o = WEBRTC_SPL_RSHIFT_W32(o, 12);
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// If output is higher than 32768, saturate it. Same with negative side
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*downsampled_ptr++ = WebRtcSpl_SatW32ToW16(o);
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}
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return 0;
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}
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