diff options
Diffstat (limited to 'drivers/isdn/mISDN/dsp_dtmf.c')
| -rw-r--r-- | drivers/isdn/mISDN/dsp_dtmf.c | 303 |
1 files changed, 303 insertions, 0 deletions
diff --git a/drivers/isdn/mISDN/dsp_dtmf.c b/drivers/isdn/mISDN/dsp_dtmf.c new file mode 100644 index 0000000..efc371c --- /dev/null +++ b/drivers/isdn/mISDN/dsp_dtmf.c @@ -0,0 +1,303 @@ +/* + * DTMF decoder. + * + * Copyright by Andreas Eversberg (jolly@eversberg.eu) + * based on different decoders such as ISDN4Linux + * + * This software may be used and distributed according to the terms + * of the GNU General Public License, incorporated herein by reference. + * + */ + +#include <linux/mISDNif.h> +#include <linux/mISDNdsp.h> +#include "core.h" +#include "dsp.h" + +#define NCOEFF 8 /* number of frequencies to be analyzed */ + +/* For DTMF recognition: + * 2 * cos(2 * PI * k / N) precalculated for all k + */ +static u64 cos2pik[NCOEFF] = +{ + /* k << 15 (source: hfc-4s/8s documentation (www.colognechip.de)) */ + 55960, 53912, 51402, 48438, 38146, 32650, 26170, 18630 +}; + +/* digit matrix */ +static char dtmf_matrix[4][4] = +{ + {'1', '2', '3', 'A'}, + {'4', '5', '6', 'B'}, + {'7', '8', '9', 'C'}, + {'*', '0', '#', 'D'} +}; + +/* dtmf detection using goertzel algorithm + * init function + */ +void dsp_dtmf_goertzel_init(struct dsp *dsp) +{ + dsp->dtmf.size = 0; + dsp->dtmf.lastwhat = '\0'; + dsp->dtmf.lastdigit = '\0'; + dsp->dtmf.count = 0; +} + +/* check for hardware or software features + */ +void dsp_dtmf_hardware(struct dsp *dsp) +{ + int hardware = 1; + + if (!dsp->features.hfc_dtmf) + hardware = 0; + + /* check for volume change */ + if (dsp->tx_volume) { + if (dsp_debug & DEBUG_DSP_DTMF) + printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, " + "because tx_volume is changed\n", + __func__, dsp->name); + hardware = 0; + } + if (dsp->rx_volume) { + if (dsp_debug & DEBUG_DSP_DTMF) + printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, " + "because rx_volume is changed\n", + __func__, dsp->name); + hardware = 0; + } + /* check if encryption is enabled */ + if (dsp->bf_enable) { + if (dsp_debug & DEBUG_DSP_DTMF) + printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, " + "because encryption is enabled\n", + __func__, dsp->name); + hardware = 0; + } + /* check if pipeline exists */ + if (dsp->pipeline.inuse) { + if (dsp_debug & DEBUG_DSP_DTMF) + printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, " + "because pipeline exists.\n", + __func__, dsp->name); + hardware = 0; + } + + dsp->dtmf.hardware = hardware; + dsp->dtmf.software = !hardware; +} + + +/************************************************************* + * calculate the coefficients of the given sample and decode * + *************************************************************/ + +/* the given sample is decoded. if the sample is not long enough for a + * complete frame, the decoding is finished and continued with the next + * call of this function. + * + * the algorithm is very good for detection with a minimum of errors. i + * tested it allot. it even works with very short tones (40ms). the only + * disadvantage is, that it doesn't work good with different volumes of both + * tones. this will happen, if accoustically coupled dialers are used. + * it sometimes detects tones during speach, which is normal for decoders. + * use sequences to given commands during calls. + * + * dtmf - points to a structure of the current dtmf state + * spl and len - the sample + * fmt - 0 = alaw, 1 = ulaw, 2 = coefficients from HFC DTMF hw-decoder + */ + +u8 +*dsp_dtmf_goertzel_decode(struct dsp *dsp, u8 *data, int len, int fmt) +{ + u8 what; + int size; + signed short *buf; + s32 sk, sk1, sk2; + int k, n, i; + s32 *hfccoeff; + s32 result[NCOEFF], tresh, treshl; + int lowgroup, highgroup; + s64 cos2pik_; + + dsp->dtmf.digits[0] = '\0'; + + /* Note: The function will loop until the buffer has not enough samples + * left to decode a full frame. + */ +again: + /* convert samples */ + size = dsp->dtmf.size; + buf = dsp->dtmf.buffer; + switch (fmt) { + case 0: /* alaw */ + case 1: /* ulaw */ + while (size < DSP_DTMF_NPOINTS && len) { + buf[size++] = dsp_audio_law_to_s32[*data++]; + len--; + } + break; + + case 2: /* HFC coefficients */ + default: + if (len < 64) { + if (len > 0) + printk(KERN_ERR "%s: coefficients have invalid " + "size. (is=%d < must=%d)\n", + __func__, len, 64); + return dsp->dtmf.digits; + } + hfccoeff = (s32 *)data; + for (k = 0; k < NCOEFF; k++) { + sk2 = (*hfccoeff++)>>4; + sk = (*hfccoeff++)>>4; + if (sk > 32767 || sk < -32767 || sk2 > 32767 + || sk2 < -32767) + printk(KERN_WARNING + "DTMF-Detection overflow\n"); + /* compute |X(k)|**2 */ + result[k] = + (sk * sk) - + (((cos2pik[k] * sk) >> 15) * sk2) + + (sk2 * sk2); + } + data += 64; + len -= 64; + goto coefficients; + break; + } + dsp->dtmf.size = size; + + if (size < DSP_DTMF_NPOINTS) + return dsp->dtmf.digits; + + dsp->dtmf.size = 0; + + /* now we have a full buffer of signed long samples - we do goertzel */ + for (k = 0; k < NCOEFF; k++) { + sk = 0; + sk1 = 0; + sk2 = 0; + buf = dsp->dtmf.buffer; + cos2pik_ = cos2pik[k]; + for (n = 0; n < DSP_DTMF_NPOINTS; n++) { + sk = ((cos2pik_*sk1)>>15) - sk2 + (*buf++); + sk2 = sk1; + sk1 = sk; + } + sk >>= 8; + sk2 >>= 8; + if (sk > 32767 || sk < -32767 || sk2 > 32767 || sk2 < -32767) + printk(KERN_WARNING "DTMF-Detection overflow\n"); + /* compute |X(k)|**2 */ + result[k] = + (sk * sk) - + (((cos2pik[k] * sk) >> 15) * sk2) + + (sk2 * sk2); + } + + /* our (squared) coefficients have been calculated, we need to process + * them. + */ +coefficients: + tresh = 0; + for (i = 0; i < NCOEFF; i++) { + if (result[i] < 0) + result[i] = 0; + if (result[i] > dsp->dtmf.treshold) { + if (result[i] > tresh) + tresh = result[i]; + } + } + + if (tresh == 0) { + what = 0; + goto storedigit; + } + + if (dsp_debug & DEBUG_DSP_DTMFCOEFF) + printk(KERN_DEBUG "a %3d %3d %3d %3d %3d %3d %3d %3d" + " tr:%3d r %3d %3d %3d %3d %3d %3d %3d %3d\n", + result[0]/10000, result[1]/10000, result[2]/10000, + result[3]/10000, result[4]/10000, result[5]/10000, + result[6]/10000, result[7]/10000, tresh/10000, + result[0]/(tresh/100), result[1]/(tresh/100), + result[2]/(tresh/100), result[3]/(tresh/100), + result[4]/(tresh/100), result[5]/(tresh/100), + result[6]/(tresh/100), result[7]/(tresh/100)); + + /* calc digit (lowgroup/highgroup) */ + lowgroup = -1; + highgroup = -1; + treshl = tresh >> 3; /* tones which are not on, must be below 9 dB */ + tresh = tresh >> 2; /* touchtones must match within 6 dB */ + for (i = 0; i < NCOEFF; i++) { + if (result[i] < treshl) + continue; /* ignore */ + if (result[i] < tresh) { + lowgroup = -1; + highgroup = -1; + break; /* noise inbetween */ + } + /* good level found. This is allowed only one time per group */ + if (i < NCOEFF/2) { + /* lowgroup */ + if (lowgroup >= 0) { + /* Bad. Another tone found. */ + lowgroup = -1; + break; + } else + lowgroup = i; + } else { + /* higroup */ + if (highgroup >= 0) { + /* Bad. Another tone found. */ + highgroup = -1; + break; + } else + highgroup = i-(NCOEFF/2); + } + } + + /* get digit or null */ + what = 0; + if (lowgroup >= 0 && highgroup >= 0) + what = dtmf_matrix[lowgroup][highgroup]; + +storedigit: + if (what && (dsp_debug & DEBUG_DSP_DTMF)) + printk(KERN_DEBUG "DTMF what: %c\n", what); + + if (dsp->dtmf.lastwhat != what) + dsp->dtmf.count = 0; + + /* the tone (or no tone) must remain 3 times without change */ + if (dsp->dtmf.count == 2) { + if (dsp->dtmf.lastdigit != what) { + dsp->dtmf.lastdigit = what; + if (what) { + if (dsp_debug & DEBUG_DSP_DTMF) + printk(KERN_DEBUG "DTMF digit: %c\n", + what); + if ((strlen(dsp->dtmf.digits)+1) + < sizeof(dsp->dtmf.digits)) { + dsp->dtmf.digits[strlen( + dsp->dtmf.digits)+1] = '\0'; + dsp->dtmf.digits[strlen( + dsp->dtmf.digits)] = what; + } + } + } + } else + dsp->dtmf.count++; + + dsp->dtmf.lastwhat = what; + + goto again; +} + + |