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313 lines
7.7 KiB
313 lines
7.7 KiB
/* |
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* DTMF decoder. |
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* |
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* Copyright by Andreas Eversberg ([email protected]) |
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* based on different decoders such as ISDN4Linux |
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* |
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* This software may be used and distributed according to the terms |
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* of the GNU General Public License, incorporated herein by reference. |
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* |
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*/ |
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#include <linux/mISDNif.h> |
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#include <linux/mISDNdsp.h> |
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#include "core.h" |
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#include "dsp.h" |
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#define NCOEFF 8 /* number of frequencies to be analyzed */ |
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/* For DTMF recognition: |
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* 2 * cos(2 * PI * k / N) precalculated for all k |
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*/ |
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static u64 cos2pik[NCOEFF] = |
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{ |
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/* k << 15 (source: hfc-4s/8s documentation (www.colognechip.de)) */ |
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55960, 53912, 51402, 48438, 38146, 32650, 26170, 18630 |
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}; |
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/* digit matrix */ |
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static char dtmf_matrix[4][4] = |
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{ |
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{'1', '2', '3', 'A'}, |
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{'4', '5', '6', 'B'}, |
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{'7', '8', '9', 'C'}, |
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{'*', '0', '#', 'D'} |
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}; |
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/* dtmf detection using goertzel algorithm |
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* init function |
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*/ |
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void dsp_dtmf_goertzel_init(struct dsp *dsp) |
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{ |
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dsp->dtmf.size = 0; |
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dsp->dtmf.lastwhat = '\0'; |
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dsp->dtmf.lastdigit = '\0'; |
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dsp->dtmf.count = 0; |
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} |
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/* check for hardware or software features |
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*/ |
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void dsp_dtmf_hardware(struct dsp *dsp) |
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{ |
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int hardware = 1; |
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if (!dsp->dtmf.enable) |
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return; |
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if (!dsp->features.hfc_dtmf) |
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hardware = 0; |
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/* check for volume change */ |
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if (dsp->tx_volume) { |
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if (dsp_debug & DEBUG_DSP_DTMF) |
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printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, " |
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"because tx_volume is changed\n", |
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__func__, dsp->name); |
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hardware = 0; |
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} |
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if (dsp->rx_volume) { |
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if (dsp_debug & DEBUG_DSP_DTMF) |
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printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, " |
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"because rx_volume is changed\n", |
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__func__, dsp->name); |
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hardware = 0; |
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} |
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/* check if encryption is enabled */ |
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if (dsp->bf_enable) { |
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if (dsp_debug & DEBUG_DSP_DTMF) |
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printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, " |
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"because encryption is enabled\n", |
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__func__, dsp->name); |
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hardware = 0; |
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} |
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/* check if pipeline exists */ |
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if (dsp->pipeline.inuse) { |
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if (dsp_debug & DEBUG_DSP_DTMF) |
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printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, " |
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"because pipeline exists.\n", |
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__func__, dsp->name); |
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hardware = 0; |
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} |
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dsp->dtmf.hardware = hardware; |
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dsp->dtmf.software = !hardware; |
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} |
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/************************************************************* |
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* calculate the coefficients of the given sample and decode * |
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*************************************************************/ |
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/* the given sample is decoded. if the sample is not long enough for a |
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* complete frame, the decoding is finished and continued with the next |
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* call of this function. |
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* |
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* the algorithm is very good for detection with a minimum of errors. i |
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* tested it allot. it even works with very short tones (40ms). the only |
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* disadvantage is, that it doesn't work good with different volumes of both |
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* tones. this will happen, if accoustically coupled dialers are used. |
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* it sometimes detects tones during speech, which is normal for decoders. |
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* use sequences to given commands during calls. |
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* |
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* dtmf - points to a structure of the current dtmf state |
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* spl and len - the sample |
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* fmt - 0 = alaw, 1 = ulaw, 2 = coefficients from HFC DTMF hw-decoder |
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*/ |
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u8 |
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*dsp_dtmf_goertzel_decode(struct dsp *dsp, u8 *data, int len, int fmt) |
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{ |
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u8 what; |
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int size; |
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signed short *buf; |
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s32 sk, sk1, sk2; |
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int k, n, i; |
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s32 *hfccoeff; |
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s32 result[NCOEFF], tresh, treshl; |
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int lowgroup, highgroup; |
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s64 cos2pik_; |
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dsp->dtmf.digits[0] = '\0'; |
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/* Note: The function will loop until the buffer has not enough samples |
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* left to decode a full frame. |
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*/ |
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again: |
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/* convert samples */ |
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size = dsp->dtmf.size; |
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buf = dsp->dtmf.buffer; |
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switch (fmt) { |
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case 0: /* alaw */ |
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case 1: /* ulaw */ |
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while (size < DSP_DTMF_NPOINTS && len) { |
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buf[size++] = dsp_audio_law_to_s32[*data++]; |
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len--; |
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} |
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break; |
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case 2: /* HFC coefficients */ |
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default: |
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if (len < 64) { |
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if (len > 0) |
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printk(KERN_ERR "%s: coefficients have invalid " |
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"size. (is=%d < must=%d)\n", |
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__func__, len, 64); |
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return dsp->dtmf.digits; |
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} |
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hfccoeff = (s32 *)data; |
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for (k = 0; k < NCOEFF; k++) { |
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sk2 = (*hfccoeff++) >> 4; |
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sk = (*hfccoeff++) >> 4; |
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if (sk > 32767 || sk < -32767 || sk2 > 32767 |
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|| sk2 < -32767) |
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printk(KERN_WARNING |
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"DTMF-Detection overflow\n"); |
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/* compute |X(k)|**2 */ |
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result[k] = |
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(sk * sk) - |
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(((cos2pik[k] * sk) >> 15) * sk2) + |
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(sk2 * sk2); |
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} |
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data += 64; |
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len -= 64; |
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goto coefficients; |
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break; |
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} |
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dsp->dtmf.size = size; |
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if (size < DSP_DTMF_NPOINTS) |
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return dsp->dtmf.digits; |
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dsp->dtmf.size = 0; |
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/* now we have a full buffer of signed long samples - we do goertzel */ |
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for (k = 0; k < NCOEFF; k++) { |
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sk = 0; |
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sk1 = 0; |
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sk2 = 0; |
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buf = dsp->dtmf.buffer; |
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cos2pik_ = cos2pik[k]; |
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for (n = 0; n < DSP_DTMF_NPOINTS; n++) { |
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sk = ((cos2pik_ * sk1) >> 15) - sk2 + (*buf++); |
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sk2 = sk1; |
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sk1 = sk; |
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} |
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sk >>= 8; |
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sk2 >>= 8; |
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if (sk > 32767 || sk < -32767 || sk2 > 32767 || sk2 < -32767) |
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printk(KERN_WARNING "DTMF-Detection overflow\n"); |
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/* compute |X(k)|**2 */ |
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result[k] = |
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(sk * sk) - |
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(((cos2pik[k] * sk) >> 15) * sk2) + |
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(sk2 * sk2); |
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} |
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/* our (squared) coefficients have been calculated, we need to process |
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* them. |
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*/ |
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coefficients: |
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tresh = 0; |
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for (i = 0; i < NCOEFF; i++) { |
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if (result[i] < 0) |
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result[i] = 0; |
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if (result[i] > dsp->dtmf.treshold) { |
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if (result[i] > tresh) |
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tresh = result[i]; |
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} |
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} |
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if (tresh == 0) { |
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what = 0; |
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goto storedigit; |
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} |
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if (dsp_debug & DEBUG_DSP_DTMFCOEFF) { |
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s32 tresh_100 = tresh/100; |
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if (tresh_100 == 0) { |
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tresh_100 = 1; |
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printk(KERN_DEBUG |
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"tresh(%d) too small set tresh/100 to 1\n", |
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tresh); |
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} |
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printk(KERN_DEBUG "a %3d %3d %3d %3d %3d %3d %3d %3d" |
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" tr:%3d r %3d %3d %3d %3d %3d %3d %3d %3d\n", |
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result[0] / 10000, result[1] / 10000, result[2] / 10000, |
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result[3] / 10000, result[4] / 10000, result[5] / 10000, |
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result[6] / 10000, result[7] / 10000, tresh / 10000, |
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result[0] / (tresh_100), result[1] / (tresh_100), |
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result[2] / (tresh_100), result[3] / (tresh_100), |
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result[4] / (tresh_100), result[5] / (tresh_100), |
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result[6] / (tresh_100), result[7] / (tresh_100)); |
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} |
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/* calc digit (lowgroup/highgroup) */ |
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lowgroup = -1; |
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highgroup = -1; |
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treshl = tresh >> 3; /* tones which are not on, must be below 9 dB */ |
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tresh = tresh >> 2; /* touchtones must match within 6 dB */ |
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for (i = 0; i < NCOEFF; i++) { |
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if (result[i] < treshl) |
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continue; /* ignore */ |
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if (result[i] < tresh) { |
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lowgroup = -1; |
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highgroup = -1; |
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break; /* noise in between */ |
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} |
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/* good level found. This is allowed only one time per group */ |
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if (i < NCOEFF / 2) { |
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/* lowgroup */ |
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if (lowgroup >= 0) { |
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/* Bad. Another tone found. */ |
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lowgroup = -1; |
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break; |
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} else |
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lowgroup = i; |
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} else { |
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/* higroup */ |
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if (highgroup >= 0) { |
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/* Bad. Another tone found. */ |
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highgroup = -1; |
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break; |
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} else |
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highgroup = i - (NCOEFF / 2); |
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} |
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} |
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/* get digit or null */ |
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what = 0; |
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if (lowgroup >= 0 && highgroup >= 0) |
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what = dtmf_matrix[lowgroup][highgroup]; |
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storedigit: |
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if (what && (dsp_debug & DEBUG_DSP_DTMF)) |
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printk(KERN_DEBUG "DTMF what: %c\n", what); |
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if (dsp->dtmf.lastwhat != what) |
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dsp->dtmf.count = 0; |
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/* the tone (or no tone) must remain 3 times without change */ |
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if (dsp->dtmf.count == 2) { |
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if (dsp->dtmf.lastdigit != what) { |
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dsp->dtmf.lastdigit = what; |
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if (what) { |
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if (dsp_debug & DEBUG_DSP_DTMF) |
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printk(KERN_DEBUG "DTMF digit: %c\n", |
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what); |
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if ((strlen(dsp->dtmf.digits) + 1) |
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< sizeof(dsp->dtmf.digits)) { |
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dsp->dtmf.digits[strlen( |
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dsp->dtmf.digits) + 1] = '\0'; |
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dsp->dtmf.digits[strlen( |
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dsp->dtmf.digits)] = what; |
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} |
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} |
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} |
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} else |
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dsp->dtmf.count++; |
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dsp->dtmf.lastwhat = what; |
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goto again; |
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}
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