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author | Christian Schneppe <christian@pix-art.de> | 2016-08-26 23:48:48 +0200 |
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committer | Christian Schneppe <christian@pix-art.de> | 2016-08-28 21:33:19 +0200 |
commit | b3b3475e93a9b08f9e35edbf74673728b560ad3b (patch) | |
tree | fc72bfce668b358310061c0a94736a0bd14e8b5d /src/main/jni/giflib/gif_hash.c | |
parent | 1f7f535d37b844dbd87447e1872c270edbca1302 (diff) |
compress videos bigger than 10 MB before sending
Diffstat (limited to 'src/main/jni/giflib/gif_hash.c')
-rw-r--r-- | src/main/jni/giflib/gif_hash.c | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/src/main/jni/giflib/gif_hash.c b/src/main/jni/giflib/gif_hash.c new file mode 100644 index 000000000..61a4d139c --- /dev/null +++ b/src/main/jni/giflib/gif_hash.c @@ -0,0 +1,132 @@ +/***************************************************************************** + +gif_hash.c -- module to support the following operations: + +1. InitHashTable - initialize hash table. +2. ClearHashTable - clear the hash table to an empty state. +2. InsertHashTable - insert one item into data structure. +3. ExistsHashTable - test if item exists in data structure. + +This module is used to hash the GIF codes during encoding. + +*****************************************************************************/ + +#include <unistd.h> +#include <stdint.h> +#include <stdlib.h> +#include <fcntl.h> +#include <stdio.h> +#include <string.h> + +#include "gif_lib.h" +#include "gif_hash.h" +#include "gif_lib_private.h" + +/* #define DEBUG_HIT_RATE Debug number of misses per hash Insert/Exists. */ + +#ifdef DEBUG_HIT_RATE +static long NumberOfTests = 0, + NumberOfMisses = 0; +#endif /* DEBUG_HIT_RATE */ + +static int KeyItem(uint32_t Item); + +/****************************************************************************** + Initialize HashTable - allocate the memory needed and clear it. * +******************************************************************************/ +GifHashTableType *_InitHashTable(void) +{ + GifHashTableType *HashTable; + + if ((HashTable = (GifHashTableType *) malloc(sizeof(GifHashTableType))) + == NULL) + return NULL; + + _ClearHashTable(HashTable); + + return HashTable; +} + +/****************************************************************************** + Routine to clear the HashTable to an empty state. * + This part is a little machine depended. Use the commented part otherwise. * +******************************************************************************/ +void _ClearHashTable(GifHashTableType *HashTable) +{ + memset(HashTable -> HTable, 0xFF, HT_SIZE * sizeof(uint32_t)); +} + +/****************************************************************************** + Routine to insert a new Item into the HashTable. The data is assumed to be * + new one. * +******************************************************************************/ +void _InsertHashTable(GifHashTableType *HashTable, uint32_t Key, int Code) +{ + int HKey = KeyItem(Key); + uint32_t *HTable = HashTable -> HTable; + +#ifdef DEBUG_HIT_RATE + NumberOfTests++; + NumberOfMisses++; +#endif /* DEBUG_HIT_RATE */ + + while (HT_GET_KEY(HTable[HKey]) != 0xFFFFFL) { +#ifdef DEBUG_HIT_RATE + NumberOfMisses++; +#endif /* DEBUG_HIT_RATE */ + HKey = (HKey + 1) & HT_KEY_MASK; + } + HTable[HKey] = HT_PUT_KEY(Key) | HT_PUT_CODE(Code); +} + +/****************************************************************************** + Routine to test if given Key exists in HashTable and if so returns its code * + Returns the Code if key was found, -1 if not. * +******************************************************************************/ +int _ExistsHashTable(GifHashTableType *HashTable, uint32_t Key) +{ + int HKey = KeyItem(Key); + uint32_t *HTable = HashTable -> HTable, HTKey; + +#ifdef DEBUG_HIT_RATE + NumberOfTests++; + NumberOfMisses++; +#endif /* DEBUG_HIT_RATE */ + + while ((HTKey = HT_GET_KEY(HTable[HKey])) != 0xFFFFFL) { +#ifdef DEBUG_HIT_RATE + NumberOfMisses++; +#endif /* DEBUG_HIT_RATE */ + if (Key == HTKey) return HT_GET_CODE(HTable[HKey]); + HKey = (HKey + 1) & HT_KEY_MASK; + } + + return -1; +} + +/****************************************************************************** + Routine to generate an HKey for the hashtable out of the given unique key. * + The given Key is assumed to be 20 bits as follows: lower 8 bits are the * + new postfix character, while the upper 12 bits are the prefix code. * + Because the average hit ratio is only 2 (2 hash references per entry), * + evaluating more complex keys (such as twin prime keys) does not worth it! * +******************************************************************************/ +static int KeyItem(uint32_t Item) +{ + return ((Item >> 12) ^ Item) & HT_KEY_MASK; +} + +#ifdef DEBUG_HIT_RATE +/****************************************************************************** + Debugging routine to print the hit ratio - number of times the hash table * + was tested per operation. This routine was used to test the KeyItem routine * +******************************************************************************/ +void HashTablePrintHitRatio(void) +{ + printf("Hash Table Hit Ratio is %ld/%ld = %ld%%.\n", + NumberOfMisses, NumberOfTests, + NumberOfMisses * 100 / NumberOfTests); +} +#endif /* DEBUG_HIT_RATE */ + +/* end */ |