view dev/xmaxc-tables.c @ 585:3c6bf0d26ee7 default tip

TW-TS-005 reader: fix maximum line length bug TW-TS-005 section 4.1 states: The maximum allowed length of each line is 80 characters, not including the OS-specific newline encoding. The implementation of this line length limit in the TW-TS-005 hex file reader function in the present suite was wrong, such that lines of the full maximum length could not be read. Fix it. Note that this bug affects comment lines too, not just actual RTP payloads. Neither Annex A nor Annex B features an RTP payload format that goes to the maximum of 40 bytes, but if a comment line goes to the maximum allowed length of 80 characters not including the terminating newline, the bug will be triggered, necessitating the present fix.
author Mychaela Falconia <falcon@freecalypso.org>
date Tue, 25 Feb 2025 07:49:28 +0000
parents 56d3fbacd115
children
line wrap: on
line source

/*
 * For libgsmfrp: if we are going to initiate comfort noise generation
 * upon receiving an invalid SID, and if we are going to harvest the
 * needed LARc and Xmaxc parameters from the last speech frame, we'll
 * need a way to compute a single mean Xmaxc from the 4 subframe Xmaxc
 * parameters of that last speech frame.
 *
 * This program generates Xmaxc dequantization and requantization tables
 * that are specifically optimized for performing this mean manipulation.
 */

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

static uint16_t dequant_table[64];
static uint8_t requant_table[1024];

static void
compute_dequant()
{
	unsigned xmaxc, dequant, step;

	dequant = 0;
	step = 1;
	for (xmaxc = 0; xmaxc < 64; xmaxc++) {
		dequant_table[xmaxc] = dequant;
		dequant += step;
		if ((xmaxc & 7) == 7 && xmaxc != 7)
			step <<= 1;
	}
}

static void
compute_requant()
{
	unsigned x, c;

	for (x = 0; x < 1024; x++) {
		for (c = 0; c < 63; c++) {
			if (x < dequant_table[c+1])
				break;
		}
		requant_table[x] = c;
	}
}

static void
print_dequant()
{
	unsigned c, r;

	puts("const uint16_t dequant_table[64] = {");
	for (c = 0; c < 64; c++) {
		r = c & 7;
		if (!r)
			putchar('\t');
		printf("%3u,", dequant_table[c]);
		if (r == 7)
			putchar('\n');
		else
			putchar(' ');
	}
	fputs("};\n\n", stdout);
}

static void
print_requant()
{
	unsigned x, r;

	puts("const uint8_t requant_table[1024] = {");
	for (x = 0; x < 1024; x++) {
		r = x & 15;
		if (!r)
			putchar('\t');
		printf("%2u,", requant_table[x]);
		if (r == 15)
			putchar('\n');
		else
			putchar(' ');
	}
	fputs("};\n", stdout);
}

main(argc, argv)
	char **argv;
{
	compute_dequant();
	compute_requant();
	print_dequant();
	print_requant();
	exit(0);
}