summaryrefslogtreecommitdiff
path: root/drivers/isdn/mISDN/dsp_dtmf.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/isdn/mISDN/dsp_dtmf.c')
-rw-r--r--drivers/isdn/mISDN/dsp_dtmf.c313
1 files changed, 313 insertions, 0 deletions
diff --git a/drivers/isdn/mISDN/dsp_dtmf.c b/drivers/isdn/mISDN/dsp_dtmf.c
new file mode 100644
index 000000000..642f30be5
--- /dev/null
+++ b/drivers/isdn/mISDN/dsp_dtmf.c
@@ -0,0 +1,313 @@
+/*
+ * 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->dtmf.enable)
+ return;
+
+ 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 speech, 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) {
+ s32 tresh_100 = tresh/100;
+
+ if (tresh_100 == 0) {
+ tresh_100 = 1;
+ printk(KERN_DEBUG
+ "tresh(%d) too small set tresh/100 to 1\n",
+ tresh);
+ }
+ 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 in between */
+ }
+ /* 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;
+}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-16 10:05:01 +0000