ref: 6a99885954277048b0d73840941dc47ede4c103a
dir: /jbig2_arith_int.c/
/* jbig2dec Copyright (c) 2001 artofcode LLC. This software is provided AS-IS with no warranty, either express or implied. This software is distributed under license and may not be copied, modified or distributed except as expressly authorized under the terms of the license contained in the file LICENSE in this distribution. For information on commercial licensing, go to http://www.artifex.com/licensing/ or contact Artifex Software, Inc., 101 Lucas Valley Road #110, San Rafael, CA 94903, U.S.A., +1(415)492-9861. $Id: jbig2_arith.c,v 1.13 2002/08/14 10:25:59 giles Exp $ */ /* Annex A */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include "os_types.h" #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); }