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lzw: Create #define for number of dictionary entry slots.

This commit is contained in:
Michael Drake 2021-03-31 19:12:38 +01:00 committed by Michael Drake
parent f66e20e017
commit 47a441f86b
1 changed files with 5 additions and 3 deletions
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8
libvips/foreign/libnsgif/lzw.c
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@ -21,6 +21,8 @@
* Decoder for GIF LZW data. * Decoder for GIF LZW data.
*/ */
/** Maximum number of dictionary entries. */
#define LZW_TABLE_ENTRY_MAX (1u << LZW_CODE_MAX)
/** /**
* Context for reading LZW data. * Context for reading LZW data.
@ -79,10 +81,10 @@ struct lzw_ctx {
uint32_t current_entry; /**< Next position in table to fill. */ uint32_t current_entry; /**< Next position in table to fill. */
/** Output value stack. */ /** Output value stack. */
uint8_t stack_base[1 << LZW_CODE_MAX]; uint8_t stack_base[LZW_TABLE_ENTRY_MAX];
/** LZW decode dictionary. Generated during decode. */ /** LZW decode dictionary. Generated during decode. */
struct lzw_dictionary_entry table[1 << LZW_CODE_MAX]; struct lzw_dictionary_entry table[LZW_TABLE_ENTRY_MAX];
}; };
@ -342,7 +344,7 @@ lzw_result lzw_decode(struct lzw_ctx *ctx,
} }
/* Add to the dictionary, only if there's space */ /* Add to the dictionary, only if there's space */
if (current_entry < (1 << LZW_CODE_MAX)) { if (current_entry < LZW_TABLE_ENTRY_MAX) {
struct lzw_dictionary_entry *entry = table + current_entry; struct lzw_dictionary_entry *entry = table + current_entry;
entry->last_value = last_value; entry->last_value = last_value;
entry->first_value = ctx->previous_code_first; entry->first_value = ctx->previous_code_first;