ref: d88cf9f4fdb0b874f9544ac54bcbf3b536665096
dir: /jbig2_arith_int.c/
/* Annex A */ #ifdef HAVE_CONFIG_H #include "config.h" #include "config_types.h" #elif _WIN32 #include "config_win32.h" #endif #ifdef HAVE_STDINT_H #include <stdint.h> #endif #include <stddef.h> #include <string.h> /* memset() */ #include "jbig2.h" #include "jbig2_priv.h" #include "jbig2_arith.h" #include "jbig2_arith_int.h" struct _Jbig2ArithIntCtx { Jbig2ArithCx IAx[512]; }; Jbig2ArithIntCtx * jbig2_arith_int_ctx_new(Jbig2Ctx *ctx) { Jbig2ArithIntCtx *result = jbig2_new(ctx, Jbig2ArithIntCtx, 1); memset(result->IAx, 0, sizeof(result->IAx)); return result; } /* A.2 */ /* Return value: -1 on error, 0 on normal value, 1 on OOB return. */ int jbig2_arith_int_decode(Jbig2ArithIntCtx *ctx, Jbig2ArithState *as, int32_t *p_result) { Jbig2ArithCx *IAx = ctx->IAx; int PREV = 1; int S, V; int bit; int n_tail, offset; int i; S = jbig2_arith_decode(as, &IAx[PREV]); PREV = (PREV << 1) | S; bit = jbig2_arith_decode(as, &IAx[PREV]); PREV = (PREV << 1) | bit; if (bit) { bit = jbig2_arith_decode(as, &IAx[PREV]); PREV = (PREV << 1) | bit; if (bit) { bit = jbig2_arith_decode(as, &IAx[PREV]); PREV = (PREV << 1) | bit; if (bit) { bit = jbig2_arith_decode(as, &IAx[PREV]); PREV = (PREV << 1) | bit; if (bit) { bit = jbig2_arith_decode(as, &IAx[PREV]); PREV = (PREV << 1) | bit; if (bit) { n_tail = 32; offset = 4436; } else { n_tail = 12; offset = 340; } } else { n_tail = 8; offset = 84; } } else { n_tail = 6; offset = 20; } } else { n_tail = 4; offset = 4; } } else { n_tail = 2; offset = 0; } V = 0; for (i = 0; i < n_tail; i++) { bit = jbig2_arith_decode(as, &IAx[PREV]); PREV = ((PREV << 1) & 511) | (PREV & 256) | bit; V = (V << 1) | bit; } V += offset; V = S ? -V : V; *p_result = V; return S && V == 0 ? 1 : 0; } void jbig2_arith_int_ctx_free(Jbig2Ctx *ctx, Jbig2ArithIntCtx *iax) { jbig2_free(ctx->allocator, iax); }