/*
* jdhuff.h
*
- * Copyright (C) 1991-1997, Thomas G. Lane.
+ * Copyright (C) 1991-1998, Thomas G. Lane.
* This file is part of the Independent JPEG Group's software.
* For conditions of distribution and use, see the accompanying README file.
*
* This file contains declarations for Huffman entropy decoding routines
- * that are shared between the sequential decoder (jdhuff.c) and the
- * progressive decoder (jdphuff.c). No other modules need to see these.
+ * that are shared between the sequential decoder (jdhuff.c), the
+ * progressive decoder (jdphuff.c) and the lossless decoder (jdlhuff.c).
+ * No other modules need to see these.
*/
/* Short forms of external names for systems with brain-damaged linkers. */
#ifdef NEED_SHORT_EXTERNAL_NAMES
-#define jpeg_make_d_derived_tbl jMkDDerived
-#define jpeg_fill_bit_buffer jFilBitBuf
-#define jpeg_huff_decode jHufDecode
+#define jpeg_make_d_derived_tbl jMkDDerived
+#define jpeg_fill_bit_buffer jFilBitBuf
+#define jpeg_huff_decode jHufDecode
#endif /* NEED_SHORT_EXTERNAL_NAMES */
/* Derived data constructed for each Huffman table */
-#define HUFF_LOOKAHEAD 8 /* # of bits of lookahead */
+#define HUFF_LOOKAHEAD 8 /* # of bits of lookahead */
typedef struct {
/* Basic tables: (element [0] of each array is unused) */
- INT32 maxcode[18]; /* largest code of length k (-1 if none) */
+ INT32 maxcode[18]; /* largest code of length k (-1 if none) */
/* (maxcode[17] is a sentinel to ensure jpeg_huff_decode terminates) */
- INT32 valoffset[17]; /* huffval[] offset for codes of length k */
+ INT32 valoffset[17]; /* huffval[] offset for codes of length k */
/* valoffset[k] = huffval[] index of 1st symbol of code length k, less
* the smallest code of length k; so given a code of length k, the
* corresponding symbol is huffval[code + valoffset[k]]
/* Expand a Huffman table definition into the derived format */
EXTERN(void) jpeg_make_d_derived_tbl
- JPP((j_decompress_ptr cinfo, boolean isDC, int tblno,
- d_derived_tbl ** pdtbl));
+ JPP((j_decompress_ptr cinfo, boolean isDC, int tblno,
+ d_derived_tbl ** pdtbl));
/*
* necessary.
*/
-typedef INT32 bit_buf_type; /* type of bit-extraction buffer */
-#define BIT_BUF_SIZE 32 /* size of buffer in bits */
+typedef INT32 bit_buf_type; /* type of bit-extraction buffer */
+#define BIT_BUF_SIZE 32 /* size of buffer in bits */
/* If long is > 32 bits on your machine, and shifting/masking longs is
* reasonably fast, making bit_buf_type be long and setting BIT_BUF_SIZE
* because not all machines measure sizeof in 8-bit bytes.
*/
-typedef struct { /* Bitreading state saved across MCUs */
- bit_buf_type get_buffer; /* current bit-extraction buffer */
- int bits_left; /* # of unused bits in it */
+typedef struct { /* Bitreading state saved across MCUs */
+ bit_buf_type get_buffer; /* current bit-extraction buffer */
+ int bits_left; /* # of unused bits in it */
} bitread_perm_state;
-typedef struct { /* Bitreading working state within an MCU */
+typedef struct { /* Bitreading working state within an MCU */
/* Current data source location */
/* We need a copy, rather than munging the original, in case of suspension */
const JOCTET * next_input_byte; /* => next byte to read from source */
- size_t bytes_in_buffer; /* # of bytes remaining in source buffer */
+ size_t bytes_in_buffer; /* # of bytes remaining in source buffer */
/* Bit input buffer --- note these values are kept in register variables,
* not in this struct, inside the inner loops.
*/
- bit_buf_type get_buffer; /* current bit-extraction buffer */
- int bits_left; /* # of unused bits in it */
+ bit_buf_type get_buffer; /* current bit-extraction buffer */
+ int bits_left; /* # of unused bits in it */
/* Pointer needed by jpeg_fill_bit_buffer. */
- j_decompress_ptr cinfo; /* back link to decompress master record */
+ j_decompress_ptr cinfo; /* back link to decompress master record */
} bitread_working_state;
/* Macros to declare and load/save bitread local variables. */
#define BITREAD_STATE_VARS \
- register bit_buf_type get_buffer; \
- register int bits_left; \
- bitread_working_state br_state
+ register bit_buf_type get_buffer; \
+ register int bits_left; \
+ bitread_working_state br_state
#define BITREAD_LOAD_STATE(cinfop,permstate) \
- br_state.cinfo = cinfop; \
- br_state.next_input_byte = cinfop->src->next_input_byte; \
- br_state.bytes_in_buffer = cinfop->src->bytes_in_buffer; \
- get_buffer = permstate.get_buffer; \
- bits_left = permstate.bits_left;
+ br_state.cinfo = cinfop; \
+ br_state.next_input_byte = cinfop->src->next_input_byte; \
+ br_state.bytes_in_buffer = cinfop->src->bytes_in_buffer; \
+ get_buffer = permstate.get_buffer; \
+ bits_left = permstate.bits_left;
#define BITREAD_SAVE_STATE(cinfop,permstate) \
- cinfop->src->next_input_byte = br_state.next_input_byte; \
- cinfop->src->bytes_in_buffer = br_state.bytes_in_buffer; \
- permstate.get_buffer = get_buffer; \
- permstate.bits_left = bits_left
+ cinfop->src->next_input_byte = br_state.next_input_byte; \
+ cinfop->src->bytes_in_buffer = br_state.bytes_in_buffer; \
+ permstate.get_buffer = get_buffer; \
+ permstate.bits_left = bits_left
/*
* These macros provide the in-line portion of bit fetching.
* before using GET_BITS, PEEK_BITS, or DROP_BITS.
* The variables get_buffer and bits_left are assumed to be locals,
* but the state struct might not be (jpeg_huff_decode needs this).
- * CHECK_BIT_BUFFER(state,n,action);
- * Ensure there are N bits in get_buffer; if suspend, take action.
+ * CHECK_BIT_BUFFER(state,n,action);
+ * Ensure there are N bits in get_buffer; if suspend, take action.
* val = GET_BITS(n);
- * Fetch next N bits.
+ * Fetch next N bits.
* val = PEEK_BITS(n);
- * Fetch next N bits without removing them from the buffer.
- * DROP_BITS(n);
- * Discard next N bits.
+ * Fetch next N bits without removing them from the buffer.
+ * DROP_BITS(n);
+ * Discard next N bits.
* The value N should be a simple variable, not an expression, because it
* is evaluated multiple times.
*/
#define CHECK_BIT_BUFFER(state,nbits,action) \
- { if (bits_left < (nbits)) { \
- if (! jpeg_fill_bit_buffer(&(state),get_buffer,bits_left,nbits)) \
- { action; } \
- get_buffer = (state).get_buffer; bits_left = (state).bits_left; } }
+ { if (bits_left < (nbits)) { \
+ if (! jpeg_fill_bit_buffer(&(state),get_buffer,bits_left,nbits)) \
+ { action; } \
+ get_buffer = (state).get_buffer; bits_left = (state).bits_left; } }
#define GET_BITS(nbits) \
- (((int) (get_buffer >> (bits_left -= (nbits)))) & ((1<<(nbits))-1))
+ (((int) (get_buffer >> (bits_left -= (nbits)))) & ((1<<(nbits))-1))
#define PEEK_BITS(nbits) \
- (((int) (get_buffer >> (bits_left - (nbits)))) & ((1<<(nbits))-1))
+ (((int) (get_buffer >> (bits_left - (nbits)))) & ((1<<(nbits))-1))
#define DROP_BITS(nbits) \
- (bits_left -= (nbits))
+ (bits_left -= (nbits))
/* Load up the bit buffer to a depth of at least nbits */
EXTERN(boolean) jpeg_fill_bit_buffer
- JPP((bitread_working_state * state, register bit_buf_type get_buffer,
- register int bits_left, int nbits));
+ JPP((bitread_working_state * state, register bit_buf_type get_buffer,
+ register int bits_left, int nbits));
/*
nb = HUFF_LOOKAHEAD+1; \
slowlabel: \
if ((result=jpeg_huff_decode(&state,get_buffer,bits_left,htbl,nb)) < 0) \
- { failaction; } \
+ { failaction; } \
get_buffer = state.get_buffer; bits_left = state.bits_left; \
} \
}
/* Out-of-line case for Huffman code fetching */
EXTERN(int) jpeg_huff_decode
- JPP((bitread_working_state * state, register bit_buf_type get_buffer,
- register int bits_left, d_derived_tbl * htbl, int min_bits));
+ JPP((bitread_working_state * state, register bit_buf_type get_buffer,
+ register int bits_left, d_derived_tbl * htbl, int min_bits));
+
+
+/* Common fields between sequential, progressive and lossless Huffman entropy
+ * decoder master structs.
+ */
+
+#define huffd_common_fields \
+ boolean insufficient_data; /* set TRUE after emmitting warning */ \
+ /* These fields are loaded into local variables at start of each MCU. \
+ * In case of suspension, we exit WITHOUT updating them. \
+ */ \
+ bitread_perm_state bitstate /* Bit buffer at start of MCU */
+
+/* Routines that are to be used by any or all of the entropy decoders are
+ * declared to receive a pointer to this structure. There are no actual
+ * instances of huffd_common_struct, only of shuff_entropy_decoder,
+ * phuff_entropy_decoder and lhuff_entropy_decoder.
+ */
+struct huffd_common_struct {
+ huffd_common_fields; /* Fields common to all decoder struct types */
+ /* Additional fields follow in an actual shuff_entropy_decoder,
+ * phuff_entropy_decoder or lhuff_entropy_decoder struct. All four structs
+ * must agree on these initial fields! (This would be a lot cleaner in C++.)
+ */
+};
+
+typedef struct huffd_common_struct * huffd_common_ptr;
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