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Gold Medal Software 2
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Gold Medal Software Volume 2 (Gold Medal) (1994).iso
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GB11CODE.C
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C/C++ Source or Header
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1992-12-15
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4KB
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/* gb11code.c - Special purpose GIF compressor routines (version 1.1). */
#include <stdio.h>
#include <string.h>
#include "uffile.h"
#include "arith.h"
#include "arithmod.h"
#include "gbcon.h"
#include "gb11code.h"
extern void *(*basic_alloc) P((size_t size),());
extern void (*basic_free) P((void *block),());
GB11_CODER *
gb11_alloc_coder()
{
GB11_CODER *gb11;
if ((gb11=basic_alloc(sizeof(GB11_CODER))) == NULL)
return NULL;
gb11->ac_order_1_cons =
basic_alloc(ARCON_NCODES*sizeof(ARCON_SMALL_CONTEXT));
if (gb11->ac_order_1_cons == NULL) {
basic_free(gb11);
return NULL;
}
return gb11;
}
void
gb11_free_coder(gb11)
GB11_CODER *gb11;
{
if (gb11 != NULL) {
if (gb11->ac_order_1_cons != NULL)
basic_free(gb11->ac_order_1_cons);
basic_free(gb11);
}
}
static void
gb11_init(gb11)
GB11_CODER *gb11;
{
int i;
arcon_big_init(&gb11->ac_order_0_con);
for (i=0; i<ARCON_NCODES; i++)
arcon_small_init(&(gb11->ac_order_1_cons[i]),ARCON_V11_SMALL_RBSIZE);
arcon_type_init(&gb11->ac_type_con);
gb11->prev = 0;
}
int
gb11_start_encoding(gb11,ff)
GB11_CODER *gb11; FFILE *ff;
{
gb11_init(gb11);
return arith_start_encoding(&gb11->ac_struct,ff);
}
int
gb11_encode_c(c,gb11)
int c; GB11_CODER *gb11;
{
int rstart,rend,rtot,t,trstart,trend,trtot;
ARCON_BIG_CONTEXT *big_con;
ARCON_SMALL_CONTEXT *small_con;
ARCON_TYPE_CONTEXT *type_con;
big_con = &gb11->ac_order_0_con;
small_con = &(gb11->ac_order_1_cons[gb11->prev]);
type_con = &gb11->ac_type_con;
if (arcon_small_find_range(small_con,c,&rstart,&rend)) {
t = 1;
rtot = arcon_small_rtot(small_con);
} else if (arcon_big_find_range(big_con,c,&rstart,&rend)) {
t = 0;
rtot = arcon_big_rtot(big_con);
} else
return -1;
if (arcon_type_find_range(type_con,t,&trstart,&trend))
trtot = arcon_type_rtot(type_con);
else
return -1;
if (arith_encode(&gb11->ac_struct,trstart,trend,trtot)<0
|| arith_encode(&gb11->ac_struct,rstart,rend,rtot)<0
|| arcon_type_add(type_con,t)<0
|| arcon_small_add(small_con,c)<0
|| (t==0 && arcon_big_add(big_con,c)<0))
return -1;
gb11->prev = c;
return 0;
}
int
gb11_end_encoding(gb11)
GB11_CODER *gb11;
{
return arith_end_encoding(&gb11->ac_struct);
}
int
gb11_start_decoding(gb11,ff)
GB11_CODER *gb11; FFILE *ff;
{
gb11_init(gb11);
return arith_start_decoding(&gb11->ac_struct,ff);
}
int
gb11_decode_c(gb11)
GB11_CODER *gb11;
{
int trstart,trend,trtot,trpos,t,rstart,rend,rtot,rpos,c;
ARCON_BIG_CONTEXT *big_con;
ARCON_SMALL_CONTEXT *small_con;
ARCON_TYPE_CONTEXT *type_con;
big_con = &gb11->ac_order_0_con;
small_con = &(gb11->ac_order_1_cons[gb11->prev]);
type_con = &gb11->ac_type_con;
trtot = arcon_type_rtot(type_con);
trpos = arith_decode_getrpos(&gb11->ac_struct,trtot);
if ((t=arcon_type_find_c(type_con,trpos,&trstart,&trend))<0
|| arith_decode_advance(&gb11->ac_struct,trstart,trend,trtot)<0
|| arcon_type_add(type_con,t)<0)
return -1;
if (t == 0) {
rtot = arcon_big_rtot(big_con);
rpos = arith_decode_getrpos(&gb11->ac_struct,rtot);
if ((c=arcon_big_find_c(big_con,rpos,&rstart,&rend))<0
|| arith_decode_advance(&gb11->ac_struct,rstart,rend,rtot)<0
|| arcon_big_add(big_con,c)<0
|| arcon_small_add(small_con,c)<0)
return -1;
} else {
rtot = arcon_small_rtot(small_con);
rpos = arith_decode_getrpos(&gb11->ac_struct,rtot);
if ((c=arcon_small_find_c(small_con,rpos,&rstart,&rend))<0
|| arith_decode_advance(&gb11->ac_struct,rstart,rend,rtot)<0
|| arcon_small_add(small_con,c)<0)
return -1;
}
gb11->prev = c;
return c;
}
int
gb11_end_decoding(gb11)
GB11_CODER *gb11;
{
return arith_end_decoding(&gb11->ac_struct);
}