Added support for signalling system no. 5.

[lcr.git] / ss5_encode.c

diff --git a/ss5_encode.c b/ss5_encode.c
new file mode 100644 (file)
index 0000000..0b2ab54
--- /dev/null
+++ b/ss5_encode.c
@@ -0,0 +1,102 @@
+/*
+ * SS5 signal coder.
+ *
+ * Copyright            by Andreas Eversberg (jolly@eversberg.eu)
+ *
+ * This software may be used and distributed according to the terms
+ * of the GNU General Public License, incorporated herein by reference.
+ *
+ */
+
+#include "main.h"
+#include "ss5_encode.h"
+
+       /* 2*PI*f/8000 */
+static double ss5_freq[9][2] = {
+       {0.0, 0},               /* 0: 0 */
+       {700,   0.19952623},    /* 1: 700, -7db */
+       {900,   0.19952623},    /* 2: 900, -7db */
+       {1100,  0.19952623},    /* 3: 1100, -7db */
+       {1300,  0.19952623},    /* 4: 1300, -7db */
+       {1500,  0.19952623},    /* 5: 1500, -7db */
+       {1700,  0.19952623},    /* 6: 1700, -7db */
+       {2400,  0.12589254},    /* 7: 2400, -9db */
+       {2600,  0.12589254},    /* 8: 2600, -9db */
+};
+
+static char ss5_digits[][3] = {
+       {'1', 1, 2},
+       {'2', 1, 3},
+       {'3', 2, 3},
+       {'4', 1, 4},
+       {'5', 2, 4},
+       {'6', 3, 4},
+       {'7', 1, 5},
+       {'8', 2, 5},
+       {'9', 3, 5},
+       {'0', 4, 5},
+       {'*', 1, 6}, /* code 11 */
+       {'#', 2, 6}, /* code 12 */
+       {'a', 3, 6}, /* KP1 */
+       {'b', 4, 6}, /* KP2 */
+       {'c', 5, 6}, /* ST */
+       {'A', 7, 0}, /* 2400 answer, acknowledge */
+       {'B', 8, 0}, /* 2600 busy */
+       {'C', 7, 8}, /* 2600+2400 clear forward */
+       {0 , 0, 0},
+};
+
+static unsigned char sintab[15+3][8192]; /* sine tables of about one second sound (error <1Hz) */
+
+/* generate sine tables */
+void ss5_sine_generate(void)
+{
+       int i, j;
+       int cycles1, cycles2;
+       double vol1, vol2, phase1, phase2;
+       signed short sample;
+
+       for (i = 0; i < 15+3; i++) {
+               /* how many cycles are within 8192 samples (rounded!) */
+               cycles1 = (int)(ss5_freq[(int)ss5_digits[i][1]][0] / 8000.0 * 8192.0 + 0.5);
+               cycles2 = (int)(ss5_freq[(int)ss5_digits[i][2]][0] / 8000.0 * 8192.0 + 0.5);
+               /* how much phase shift within one cycle */
+               phase1 = 2.0 * 3.14159265 * cycles1 / 8192.0;
+               phase2 = 2.0 * 3.14159265 * cycles2 / 8192.0;
+               /* volume */
+               vol1 = ss5_freq[(int)ss5_digits[i][1]][1] * 32768.0;
+               vol2 = ss5_freq[(int)ss5_digits[i][2]][1] * 32768.0;
+               for (j = 0; j < 8192; j++) {
+                       sample = (int)(sin(phase1 * j) * vol1);
+                       sample += (int)(sin(phase2 * j) * vol2);
+                       sintab[i][j] = audio_s16_to_law[sample & 0xffff];
+               }
+       }
+}
+
+/* encode digit at given sample_nr with given lengt and return law-encoded audio */
+unsigned char *ss5_encode(unsigned char *buffer, int len, char digit, int sample_nr)
+{
+       int i, j;
+
+       /* get frequency from digit */
+       i = 0;
+       while(ss5_digits[i][0]) {
+               if (digit == ss5_digits[i][0])
+                       break;
+               i++;
+       }
+       if (!ss5_digits[i][0]) {
+               PERROR("Digit '%c' does not exist.\n", digit);
+               memset(buffer, audio_s16_to_law[0], sizeof(buffer));
+               return buffer;
+       }
+
+       /* copy tones */
+       for (j = 0; j < len; j++)
+               *buffer++ = sintab[i][sample_nr++ & 8191];
+
+       return buffer;
+}
+
+