FreeCalypso > hg > gsm-codec-lib
view dev/efr-sid-insert.c @ 183:452c1d5a6268
libgsmefr BFI w/o data: emit zero output after decoder reset
In real-life usage, each EFR decoder session will most likely begin
with lots of BFI frames before the first real frame arrives. However,
because the spec-defined home state of the decoder is speech rather
than CN, our regular logic for BFI w/o data would have to feed
pseudorandom noise to the decoder (in the "fixed codebook excitation
pulses" part), which is silly to do at the beginning of the decoder
session right out of reset. Therefore, let's check reset_flag_old,
and if we are still in the reset state, simply emit zero output.
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Tue, 03 Jan 2023 00:12:18 +0000 |
parents | 3b5958f28a40 |
children |
line wrap: on
line source
/* * We need to implement a function that inserts the 95 bit wide SID * codeword into the frame, and we would like to do it more efficiently * than calling a "set bit" function for each of the 95 bits. This * program will produce a more efficient solution. */ #include <stdio.h> #include <stdint.h> #include <stdlib.h> #include <string.h> static const uint8_t SID_codeword_bit_idx[95] = { 45, 46, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 94, 95, 96, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221 }; static void set_bit(uint8_t *frame, unsigned bitnum) { unsigned bytenum = bitnum >> 3; unsigned bit_in_byte = 7 - (bitnum & 7); unsigned bitmask = 1 << bit_in_byte; frame[bytenum] |= bitmask; } main(argc, argv) char **argv; { uint8_t bytes[31]; unsigned n; memset(bytes, 0, 31); for (n = 0; n < 95; n++) set_bit(bytes, SID_codeword_bit_idx[n] + 4); for (n = 0; n < 31; n++) if (bytes[n]) printf("\tframe[%u] |= 0x%02X;\n", n, bytes[n]); exit(0); }