/*
 * This program reads an 8-bit PCM recording in either A-law or mu-law
 * encoding (needs to be specified on the command line) and converts it
 * to 16-bit linear PCM.  Both input and output file formats are raw binary;
 * the output format is robe by default or can be changed to LE via
 * an additional command line argument.
 *
 * The expansion tables for A-law and mu-law have been generated by
 * developer aid programs in the ../dev directory.
 */

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>

uint16_t pcma_decode_table[256] = {
	60032, 60288, 59520, 59776, 61056, 61312, 60544, 60800,
	57984, 58240, 57472, 57728, 59008, 59264, 58496, 58752,
	62784, 62912, 62528, 62656, 63296, 63424, 63040, 63168,
	61760, 61888, 61504, 61632, 62272, 62400, 62016, 62144,
	43520, 44544, 41472, 42496, 47616, 48640, 45568, 46592,
	35328, 36352, 33280, 34304, 39424, 40448, 37376, 38400,
	54528, 55040, 53504, 54016, 56576, 57088, 55552, 56064,
	50432, 50944, 49408, 49920, 52480, 52992, 51456, 51968,
	65192, 65208, 65160, 65176, 65256, 65272, 65224, 65240,
	65064, 65080, 65032, 65048, 65128, 65144, 65096, 65112,
	65448, 65464, 65416, 65432, 65512, 65528, 65480, 65496,
	65320, 65336, 65288, 65304, 65384, 65400, 65352, 65368,
	64160, 64224, 64032, 64096, 64416, 64480, 64288, 64352,
	63648, 63712, 63520, 63584, 63904, 63968, 63776, 63840,
	64848, 64880, 64784, 64816, 64976, 65008, 64912, 64944,
	64592, 64624, 64528, 64560, 64720, 64752, 64656, 64688,
	 5504,  5248,  6016,  5760,  4480,  4224,  4992,  4736,
	 7552,  7296,  8064,  7808,  6528,  6272,  7040,  6784,
	 2752,  2624,  3008,  2880,  2240,  2112,  2496,  2368,
	 3776,  3648,  4032,  3904,  3264,  3136,  3520,  3392,
	22016, 20992, 24064, 23040, 17920, 16896, 19968, 18944,
	30208, 29184, 32256, 31232, 26112, 25088, 28160, 27136,
	11008, 10496, 12032, 11520,  8960,  8448,  9984,  9472,
	15104, 14592, 16128, 15616, 13056, 12544, 14080, 13568,
	  344,   328,   376,   360,   280,   264,   312,   296,
	  472,   456,   504,   488,   408,   392,   440,   424,
	   88,    72,   120,   104,    24,     8,    56,    40,
	  216,   200,   248,   232,   152,   136,   184,   168,
	 1376,  1312,  1504,  1440,  1120,  1056,  1248,  1184,
	 1888,  1824,  2016,  1952,  1632,  1568,  1760,  1696,
	  688,   656,   752,   720,   560,   528,   624,   592,
	  944,   912,  1008,   976,   816,   784,   880,   848,
};

uint16_t pcmu_decode_table[256] = {
	33412, 34436, 35460, 36484, 37508, 38532, 39556, 40580,
	41604, 42628, 43652, 44676, 45700, 46724, 47748, 48772,
	49540, 50052, 50564, 51076, 51588, 52100, 52612, 53124,
	53636, 54148, 54660, 55172, 55684, 56196, 56708, 57220,
	57604, 57860, 58116, 58372, 58628, 58884, 59140, 59396,
	59652, 59908, 60164, 60420, 60676, 60932, 61188, 61444,
	61636, 61764, 61892, 62020, 62148, 62276, 62404, 62532,
	62660, 62788, 62916, 63044, 63172, 63300, 63428, 63556,
	63652, 63716, 63780, 63844, 63908, 63972, 64036, 64100,
	64164, 64228, 64292, 64356, 64420, 64484, 64548, 64612,
	64660, 64692, 64724, 64756, 64788, 64820, 64852, 64884,
	64916, 64948, 64980, 65012, 65044, 65076, 65108, 65140,
	65164, 65180, 65196, 65212, 65228, 65244, 65260, 65276,
	65292, 65308, 65324, 65340, 65356, 65372, 65388, 65404,
	65416, 65424, 65432, 65440, 65448, 65456, 65464, 65472,
	65480, 65488, 65496, 65504, 65512, 65520, 65528,     0,
	32124, 31100, 30076, 29052, 28028, 27004, 25980, 24956,
	23932, 22908, 21884, 20860, 19836, 18812, 17788, 16764,
	15996, 15484, 14972, 14460, 13948, 13436, 12924, 12412,
	11900, 11388, 10876, 10364,  9852,  9340,  8828,  8316,
	 7932,  7676,  7420,  7164,  6908,  6652,  6396,  6140,
	 5884,  5628,  5372,  5116,  4860,  4604,  4348,  4092,
	 3900,  3772,  3644,  3516,  3388,  3260,  3132,  3004,
	 2876,  2748,  2620,  2492,  2364,  2236,  2108,  1980,
	 1884,  1820,  1756,  1692,  1628,  1564,  1500,  1436,
	 1372,  1308,  1244,  1180,  1116,  1052,   988,   924,
	  876,   844,   812,   780,   748,   716,   684,   652,
	  620,   588,   556,   524,   492,   460,   428,   396,
	  372,   356,   340,   324,   308,   292,   276,   260,
	  244,   228,   212,   196,   180,   164,   148,   132,
	  120,   112,   104,    96,    88,    80,    72,    64,
	   56,    48,    40,    32,    24,    16,     8,     0,
};

main(argc, argv)
	char **argv;
{
	uint16_t *exp_table;
	int little_endian;
	FILE *inf, *outf;
	int inp;
	unsigned out;

	if (argc < 4 || argc > 5) {
usage:		fprintf(stderr,
			"usage: %s alaw|ulaw input.pcm8 output.pcm16 [le]\n",
			argv[0]);
		exit(1);
	}
	if (!strcmp(argv[1], "alaw"))
		exp_table = pcma_decode_table;
	else if (!strcmp(argv[1], "ulaw"))
		exp_table = pcmu_decode_table;
	else
		goto usage;
	if (argc == 4)
		little_endian = 0;
	else {
		if (strcmp(argv[4], "le"))
			goto usage;
		little_endian = 1;
	}
	inf = fopen(argv[2], "r");
	if (!inf) {
		perror(argv[2]);
		exit(1);
	}
	outf = fopen(argv[3], "w");
	if (!outf) {
		perror(argv[3]);
		exit(1);
	}
	for (;;) {
		inp = getc(inf);
		if (inp == EOF)
			break;
		out = exp_table[inp];
		if (little_endian) {
			putc(out & 0xFF, outf);
			putc((out >> 8) & 0xFF, outf);
		} else {
			putc((out >> 8) & 0xFF, outf);
			putc(out & 0xFF, outf);
		}
	}
	fclose(outf);
	exit(0);
}