147 lines
4.9 KiB
C
147 lines
4.9 KiB
C
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/*
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* decmacro.h
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*
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* Macros used by the decoder
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*/
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/*
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* decode an element from the aligned offset tree, without checking
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* for the end of the input data
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*/
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#define DECODE_ALIGNED_NOEOFCHECK(j) \
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(j) = context->dec_aligned_table[dec_bitbuf >> (32-ALIGNED_TABLE_BITS)]; \
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FILL_BUF_NOEOFCHECK(context->dec_aligned_len[(j)]);
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/*
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* Decode an element from the main tree
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* Check for EOF
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*/
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#define DECODE_MAIN_TREE(j) \
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j = context->dec_main_tree_table[dec_bitbuf >> (32-MAIN_TREE_TABLE_BITS)]; \
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if (j < 0) \
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{ \
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ulong mask = (1L << (32-1-MAIN_TREE_TABLE_BITS)); \
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do \
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{ \
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j = -j; \
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if (dec_bitbuf & mask) \
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j = context->dec_main_tree_left_right[j*2+1]; \
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else \
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j = context->dec_main_tree_left_right[j*2]; \
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mask >>= 1; \
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} while (j < 0); \
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} \
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FILL_BUF_FULLCHECK(context->dec_main_tree_len[j]);
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/*
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* Decode an element from the secondary length tree
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* No checking for EOF
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*/
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#define DECODE_LEN_TREE_NOEOFCHECK(matchlen) \
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matchlen = context->dec_secondary_length_tree_table[dec_bitbuf >> (32-SECONDARY_LEN_TREE_TABLE_BITS)]; \
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if (matchlen < 0) \
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{ \
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ulong mask = (1L << (32-1-SECONDARY_LEN_TREE_TABLE_BITS)); \
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do \
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{ \
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matchlen = -matchlen; \
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if (dec_bitbuf & mask) \
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matchlen = context->dec_secondary_length_tree_left_right[matchlen*2+1];\
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else \
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matchlen = context->dec_secondary_length_tree_left_right[matchlen*2]; \
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mask >>= 1; \
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} while (matchlen < 0); \
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} \
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FILL_BUF_NOEOFCHECK(context->dec_secondary_length_tree_len[matchlen]); \
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matchlen += NUM_PRIMARY_LENGTHS;
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/*
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* read n bits from input stream into dest_var, but don't
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* check for EOF
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*/
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#define GET_BITS_NOEOFCHECK(N,DEST_VAR) \
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{ \
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DEST_VAR = dec_bitbuf >> (32-(N)); \
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FILL_BUF_NOEOFCHECK((N)); \
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}
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/* same as above, but don't check for EOF */
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#define GET_BITS17_NOEOFCHECK(N,DEST_VAR) \
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{ \
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DEST_VAR = dec_bitbuf >> (32-(N)); \
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FILL_BUF17_NOEOFCHECK((N)); \
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}
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/*
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* Remove n bits from the input stream
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* handles 1 <= n <= 17
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*
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* FORCE an EOF check ALWAYS, whether or not we read in more
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* bytes from memory.
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*
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* This is used to ensure that we always get an EOF check often enough
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* to not overrun the extra bytes in the buffer.
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*
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* This routine is used ONLY when decoding the main tree element,
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* where we know that the code we read in will be 16 bits or less
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* in length. Therefore we don't have to check for bitcount going
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* less than zero, twice.
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*/
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#define FILL_BUF_FULLCHECK(N) \
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{ \
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if (dec_input_curpos >= dec_end_input_pos) \
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return -1; \
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dec_bitbuf <<= (N); \
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dec_bitcount -= (N); \
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if (dec_bitcount <= 0) \
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{ \
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dec_bitbuf |= ((((ulong) *dec_input_curpos | (((ulong) *(dec_input_curpos+1)) << 8))) << (-dec_bitcount)); \
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dec_input_curpos += 2; \
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dec_bitcount += 16; \
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} \
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}
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/*
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* Same as above, but no EOF check
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*
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* This is used when we know we will not run out of input
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*/
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#define FILL_BUF_NOEOFCHECK(N) \
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{ \
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dec_bitbuf <<= (N); \
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dec_bitcount -= (N); \
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if (dec_bitcount <= 0) \
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{ \
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dec_bitbuf |= ((((ulong) *dec_input_curpos | (((ulong) *(dec_input_curpos+1)) << 8))) << (-dec_bitcount)); \
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dec_input_curpos += 2; \
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dec_bitcount += 16; \
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} \
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}
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/*
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* Same as above, but handles n=17 bits
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*/
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#define FILL_BUF17_NOEOFCHECK(N) \
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{ \
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dec_bitbuf <<= (N); \
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dec_bitcount -= (N); \
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if (dec_bitcount <= 0) \
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{ \
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dec_bitbuf |= ((((ulong) *dec_input_curpos | (((ulong) *(dec_input_curpos+1)) << 8))) << (-dec_bitcount)); \
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dec_input_curpos += 2; \
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dec_bitcount += 16; \
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if (dec_bitcount <= 0) \
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{ \
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dec_bitbuf |= ((((ulong) *dec_input_curpos | (((ulong) *(dec_input_curpos+1)) << 8))) << (-dec_bitcount)); \
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dec_input_curpos += 2; \
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dec_bitcount += 16; \
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} \
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} \
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}
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