92 lines
2.2 KiB
C
92 lines
2.2 KiB
C
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/*
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* Copyright 1996 by Jutta Degener and Carsten Bormann, Technische
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* Universitaet Berlin. See the accompanying file "COPYRIGHT" for
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* details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
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*/
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/*$Header*/
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/* Generate code to pack a bit array from a name:#bits description,
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* WAV #49 style.
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*/
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#include <stdio.h>
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#include "taste.h"
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#include "proto.h"
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#include <limits.h>
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/* This module goes back to one Jeff Chilton used for his implementation
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* of the #49 WAV GSM format. (In his original patch 8, it replaced
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* bitter.c.)
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*
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* In Microsoft's WAV #49 version of the GSM format, two 32 1/2
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* byte GSM frames are packed together to make one WAV frame, and
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* the GSM parameters are packed into bytes right-to-left rather
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* than left-to-right.
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*
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* That is, where toast's GSM format writes
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*
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* aaaaaabb bbbbcccc cdddddee ...
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* ___1____ ___2____ ___3____
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*
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* for parameters a (6 bits), b (6 bits), c (5 bits), d (5 bits), e ..
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* the WAV format has
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*
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* bbaaaaaa ccccbbbb eedddddc ...
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* ___1____ ___2____ ___3____
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*
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* (This format looks a lot prettier if one pictures octets coming
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* in through a fifo queue from the left, rather than waiting in the
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* right-hand remainder of a C array.)
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*/
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#define WORD_BITS 16 /* sizeof(uword) * CHAR_BIT on the
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* target architecture---if this isn't 16,
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* you're in trouble with this library anyway.
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*/
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#define BYTE_BITS 8 /* CHAR_BIT on the target architecture---
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* if this isn't 8, you're in *deep* trouble.
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*/
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void write_code P2((s_spex, n_spex), struct spex * s_spex, int n_spex)
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{
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struct spex * sp = s_spex;
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int n_in = 0;
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printf("uword sr = 0;\n");
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for (; n_spex > 0; n_spex--, sp++) {
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/* insert old
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* new var value unused
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* here
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*
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* [____________xxxxxx**********]
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*
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* <----- n_in ------>
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*/
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printf("sr = sr >> %d | %s << %d;\n",
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sp->varsize,
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sp->var,
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WORD_BITS - sp->varsize);
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n_in += sp->varsize;
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while (n_in >= BYTE_BITS) {
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printf("*c++ = sr >> %d;\n",
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WORD_BITS - n_in);
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n_in -= BYTE_BITS;
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}
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}
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while (n_in >= BYTE_BITS) {
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printf("*c++ = sr >> %d;\n", WORD_BITS - n_in);
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n_in -= BYTE_BITS;
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}
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if (n_in > 0) {
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fprintf(stderr, "warning: %d bits left over\n", n_in);
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}
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}
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