diff options
| -rw-r--r-- | compress.c | 649 |
1 files changed, 649 insertions, 0 deletions
diff --git a/compress.c b/compress.c new file mode 100644 index 0000000..e8cd8ab --- /dev/null +++ b/compress.c @@ -0,0 +1,649 @@ +/** + @file compress.c + @brief An adaptive order-2 PPM range coder +*/ +#define ENET_BUILDING_LIB 1 +#include <string.h> +#include "enet/enet.h" + +typedef struct _ENetSymbol +{ + /* binary indexed tree of symbols */ + enet_uint8 value; + enet_uint8 count; + enet_uint16 under; + enet_uint16 left, right; + + /* context defined by this symbol */ + enet_uint16 symbols; + enet_uint16 escapes; + enet_uint16 total; + enet_uint16 parent; +} ENetSymbol; + +/* adaptation constants tuned aggressively for small packet sizes rather than large file compression */ +enum +{ + ENET_RANGE_CODER_TOP = 1<<24, + ENET_RANGE_CODER_BOTTOM = 1<<16, + + ENET_CONTEXT_SYMBOL_DELTA = 3, + ENET_CONTEXT_SYMBOL_MINIMUM = 1, + ENET_CONTEXT_ESCAPE_MINIMUM = 1, + + ENET_SUBCONTEXT_ORDER = 2, + ENET_SUBCONTEXT_SYMBOL_DELTA = 2, + ENET_SUBCONTEXT_ESCAPE_DELTA = 5 +}; + +/* context exclusion roughly halves compression speed, so disable for now */ +#undef ENET_CONTEXT_EXCLUSION + +typedef struct _ENetRangeCoder +{ + /* only allocate enough symbols for reasonable MTUs, would need to be larger for large file compression */ + ENetSymbol symbols[4096]; +} ENetRangeCoder; + +void * +enet_range_coder_create (void) +{ + ENetRangeCoder * rangeCoder = (ENetRangeCoder *) enet_malloc (sizeof (ENetRangeCoder)); + if (rangeCoder == NULL) + return NULL; + + return rangeCoder; +} + +void +enet_range_coder_destroy (void * context) +{ + ENetRangeCoder * rangeCoder = (ENetRangeCoder *) context; + if (rangeCoder == NULL) + return; + + enet_free (rangeCoder); +} + +#define ENET_SYMBOL_CREATE(symbol, value_, count_) \ +{ \ + symbol = & rangeCoder -> symbols [nextSymbol ++]; \ + symbol -> value = value_; \ + symbol -> count = count_; \ + symbol -> under = count_; \ + symbol -> left = 0; \ + symbol -> right = 0; \ + symbol -> symbols = 0; \ + symbol -> escapes = 0; \ + symbol -> total = 0; \ + symbol -> parent = 0; \ +} + +#define ENET_CONTEXT_CREATE(context, escapes_, minimum) \ +{ \ + ENET_SYMBOL_CREATE (context, 0, 0); \ + (context) -> escapes = escapes_; \ + (context) -> total = escapes_ + 256*minimum; \ + (context) -> symbols = 0; \ +} + +static enet_uint16 +enet_symbol_rescale (ENetSymbol * symbol) +{ + enet_uint16 total = 0; + for (;;) + { + symbol -> count -= symbol->count >> 1; + symbol -> under = symbol -> count; + if (symbol -> left) + symbol -> under += enet_symbol_rescale (symbol + symbol -> left); + total += symbol -> under; + if (! symbol -> right) break; + symbol += symbol -> right; + } + return total; +} + +#define ENET_CONTEXT_RESCALE(context, minimum) \ +{ \ + (context) -> total = (context) -> symbols ? enet_symbol_rescale ((context) + (context) -> symbols) : 0; \ + (context) -> escapes -= (context) -> escapes >> 1; \ + (context) -> total += (context) -> escapes + 256*minimum; \ +} + +#define ENET_RANGE_CODER_OUTPUT(value) \ +{ \ + if (outData >= outEnd) \ + return 0; \ + * outData ++ = value; \ +} + +#define ENET_RANGE_CODER_ENCODE(under, count, total) \ +{ \ + encodeRange /= (total); \ + encodeLow += (under) * encodeRange; \ + encodeRange *= (count); \ + for (;;) \ + { \ + if((encodeLow ^ (encodeLow + encodeRange)) >= ENET_RANGE_CODER_TOP) \ + { \ + if(encodeRange >= ENET_RANGE_CODER_BOTTOM) break; \ + encodeRange = -encodeLow & (ENET_RANGE_CODER_BOTTOM - 1); \ + } \ + ENET_RANGE_CODER_OUTPUT (encodeLow >> 24); \ + encodeRange <<= 8; \ + encodeLow <<= 8; \ + } \ +} + +#define ENET_RANGE_CODER_FLUSH \ +{ \ + while (encodeLow) \ + { \ + ENET_RANGE_CODER_OUTPUT (encodeLow >> 24); \ + encodeLow <<= 8; \ + } \ +} + +#define ENET_RANGE_CODER_FREE_SYMBOLS \ +{ \ + if (nextSymbol >= sizeof (rangeCoder -> symbols) / sizeof (ENetSymbol) - ENET_SUBCONTEXT_ORDER ) \ + { \ + nextSymbol = 0; \ + ENET_CONTEXT_CREATE (root, ENET_CONTEXT_ESCAPE_MINIMUM, ENET_CONTEXT_SYMBOL_MINIMUM); \ + predicted = 0; \ + order = 0; \ + } \ +} + +#define ENET_CONTEXT_ENCODE(context, symbol_, value_, under_, count_, update, minimum) \ +{ \ + under_ = value*minimum; \ + count_ = minimum; \ + if (! (context) -> symbols) \ + { \ + ENET_SYMBOL_CREATE (symbol_, value_, update); \ + (context) -> symbols = symbol_ - (context); \ + } \ + else \ + { \ + ENetSymbol * node = (context) + (context) -> symbols; \ + for (;;) \ + { \ + if (value_ < node -> value) \ + { \ + node -> under += update; \ + if (node -> left) { node += node -> left; continue; } \ + ENET_SYMBOL_CREATE (symbol_, value_, update); \ + node -> left = symbol_ - node; \ + } \ + else \ + if (value_ > node -> value) \ + { \ + under_ += node -> under; \ + if (node -> right) { node += node -> right; continue; } \ + ENET_SYMBOL_CREATE (symbol_, value_, update); \ + node -> right = symbol_ - node; \ + } \ + else \ + { \ + count_ += node -> count; \ + under_ += node -> under - node -> count; \ + node -> under += update; \ + node -> count += update; \ + symbol_ = node; \ + } \ + break; \ + } \ + } \ +} + +#ifdef ENET_CONTEXT_EXCLUSION +static const ENetSymbol emptyContext = { 0, 0, 0, 0, 0, 0, 0, 0, 0 }; + +#define ENET_CONTEXT_WALK(context, body) \ +{ \ + const ENetSymbol * node = (context) + (context) -> symbols; \ + const ENetSymbol * stack [256]; \ + size_t stackSize = 0; \ + while (node -> left) \ + { \ + stack [stackSize ++] = node; \ + node += node -> left; \ + } \ + for (;;) \ + { \ + body; \ + if (node -> right) \ + { \ + node += node -> right; \ + while (node -> left) \ + { \ + stack [stackSize ++] = node; \ + node += node -> left; \ + } \ + } \ + else \ + if (stackSize <= 0) \ + break; \ + else \ + node = stack [-- stackSize]; \ + } \ +} + +#define ENET_CONTEXT_ENCODE_EXCLUDE(context, value_, under, total, minimum) \ +ENET_CONTEXT_WALK(context, { \ + if (node -> value != value_) \ + { \ + enet_uint16 parentCount = rangeCoder -> symbols [node -> parent].count + minimum; \ + if (node -> value < value_) \ + under -= parentCount; \ + total -= parentCount; \ + } \ +}) +#endif + +size_t +enet_range_coder_compress (void * context, const ENetBuffer * inBuffers, size_t inBufferCount, size_t inLimit, enet_uint8 * outData, size_t outLimit) +{ + ENetRangeCoder * rangeCoder = (ENetRangeCoder *) context; + enet_uint8 * outStart = outData, * outEnd = & outData [outLimit]; + const enet_uint8 * inData, * inEnd; + enet_uint32 encodeLow = 0, encodeRange = ~0; + ENetSymbol * root; + enet_uint16 predicted = 0; + size_t order = 0, nextSymbol = 0; + + if (rangeCoder == NULL || inBufferCount <= 0 || inLimit <= 0) + return 0; + + inData = (const enet_uint8 *) inBuffers -> data; + inEnd = & inData [inBuffers -> dataLength]; + inBuffers ++; + inBufferCount --; + + ENET_CONTEXT_CREATE (root, ENET_CONTEXT_ESCAPE_MINIMUM, ENET_CONTEXT_SYMBOL_MINIMUM); + + for (;;) + { + ENetSymbol * subcontext, * symbol; +#ifdef ENET_CONTEXT_EXCLUSION + const ENetSymbol * childContext = & emptyContext; +#endif + enet_uint8 value; + enet_uint16 count, under, * parent = & predicted, total; + if (inData >= inEnd) + { + if (inBufferCount <= 0) + break; + inData = (const enet_uint8 *) inBuffers -> data; + inEnd = & inData [inBuffers -> dataLength]; + inBuffers ++; + inBufferCount --; + } + value = * inData ++; + + for (subcontext = & rangeCoder -> symbols [predicted]; + subcontext != root; +#ifdef ENET_CONTEXT_EXCLUSION + childContext = subcontext, +#endif + subcontext = & rangeCoder -> symbols [subcontext -> parent]) + { + ENET_CONTEXT_ENCODE (subcontext, symbol, value, under, count, ENET_SUBCONTEXT_SYMBOL_DELTA, 0); + * parent = symbol - rangeCoder -> symbols; + parent = & symbol -> parent; + total = subcontext -> total; +#ifdef ENET_CONTEXT_EXCLUSION + if (childContext -> total > ENET_SUBCONTEXT_SYMBOL_DELTA + ENET_SUBCONTEXT_ESCAPE_DELTA) + ENET_CONTEXT_ENCODE_EXCLUDE (childContext, value, under, total, 0); +#endif + if (count > 0) + { + ENET_RANGE_CODER_ENCODE (subcontext -> escapes + under, count, total); + } + else + { + if (subcontext -> escapes > 0 && subcontext -> escapes < total) + ENET_RANGE_CODER_ENCODE (0, subcontext -> escapes, total); + subcontext -> escapes += ENET_SUBCONTEXT_ESCAPE_DELTA; + subcontext -> total += ENET_SUBCONTEXT_ESCAPE_DELTA; + } + subcontext -> total += ENET_SUBCONTEXT_SYMBOL_DELTA; + if (count > 0xFF - 2*ENET_SUBCONTEXT_SYMBOL_DELTA || subcontext -> total > ENET_RANGE_CODER_BOTTOM - 0x100) + ENET_CONTEXT_RESCALE (subcontext, 0); + if (count > 0) goto nextInput; + } + + ENET_CONTEXT_ENCODE (root, symbol, value, under, count, ENET_CONTEXT_SYMBOL_DELTA, ENET_CONTEXT_SYMBOL_MINIMUM); + * parent = symbol - rangeCoder -> symbols; + parent = & symbol -> parent; + total = root -> total; +#ifdef ENET_CONTEXT_EXCLUSION + if (childContext -> total > ENET_SUBCONTEXT_SYMBOL_DELTA + ENET_SUBCONTEXT_ESCAPE_DELTA) + ENET_CONTEXT_ENCODE_EXCLUDE (childContext, value, under, total, ENET_CONTEXT_SYMBOL_MINIMUM); +#endif + ENET_RANGE_CODER_ENCODE (root -> escapes + under, count, total); + root -> total += ENET_CONTEXT_SYMBOL_DELTA; + if (count > 0xFF - 2*ENET_CONTEXT_SYMBOL_DELTA + ENET_CONTEXT_SYMBOL_MINIMUM || root -> total > ENET_RANGE_CODER_BOTTOM - 0x100) + ENET_CONTEXT_RESCALE (root, ENET_CONTEXT_SYMBOL_MINIMUM); + + nextInput: + if (order >= ENET_SUBCONTEXT_ORDER) + predicted = rangeCoder -> symbols [predicted].parent; + else + order ++; + ENET_RANGE_CODER_FREE_SYMBOLS; + } + + ENET_RANGE_CODER_FLUSH; + + return (size_t) (outData - outStart); +} + +#define ENET_RANGE_CODER_SEED \ +{ \ + if (inData < inEnd) decodeCode |= * inData ++ << 24; \ + if (inData < inEnd) decodeCode |= * inData ++ << 16; \ + if (inData < inEnd) decodeCode |= * inData ++ << 8; \ + if (inData < inEnd) decodeCode |= * inData ++; \ +} + +#define ENET_RANGE_CODER_READ(total) ((decodeCode - decodeLow) / (decodeRange /= (total))) + +#define ENET_RANGE_CODER_DECODE(under, count, total) \ +{ \ + decodeLow += (under) * decodeRange; \ + decodeRange *= (count); \ + for (;;) \ + { \ + if((decodeLow ^ (decodeLow + decodeRange)) >= ENET_RANGE_CODER_TOP) \ + { \ + if(decodeRange >= ENET_RANGE_CODER_BOTTOM) break; \ + decodeRange = -decodeLow & (ENET_RANGE_CODER_BOTTOM - 1); \ + } \ + decodeCode <<= 8; \ + if (inData < inEnd) \ + decodeCode |= * inData ++; \ + decodeRange <<= 8; \ + decodeLow <<= 8; \ + } \ +} + +#define ENET_CONTEXT_DECODE(context, symbol_, code, value_, under_, count_, update, minimum, createRoot, visitNode, createRight, createLeft) \ +{ \ + under_ = 0; \ + count_ = minimum; \ + if (! (context) -> symbols) \ + { \ + createRoot; \ + } \ + else \ + { \ + ENetSymbol * node = (context) + (context) -> symbols; \ + for (;;) \ + { \ + enet_uint16 after = under_ + node -> under + (node -> value + 1)*minimum, before = node -> count + minimum; \ + visitNode; \ + if (code >= after) \ + { \ + under_ += node -> under; \ + if (node -> right) { node += node -> right; continue; } \ + createRight; \ + } \ + else \ + if (code < after - before) \ + { \ + node -> under += update; \ + if (node -> left) { node += node -> left; continue; } \ + createLeft; \ + } \ + else \ + { \ + value_ = node -> value; \ + count_ += node -> count; \ + under_ = after - before; \ + node -> under += update; \ + node -> count += update; \ + symbol_ = node; \ + } \ + break; \ + } \ + } \ +} + +#define ENET_CONTEXT_TRY_DECODE(context, symbol_, code, value_, under_, count_, update, minimum, exclude) \ +ENET_CONTEXT_DECODE (context, symbol_, code, value_, under_, count_, update, minimum, return 0, exclude (node -> value, after, before), return 0, return 0) + +#define ENET_CONTEXT_ROOT_DECODE(context, symbol_, code, value_, under_, count_, update, minimum, exclude) \ +ENET_CONTEXT_DECODE (context, symbol_, code, value_, under_, count_, update, minimum, \ + { \ + value_ = code / minimum; \ + under_ = code - code%minimum; \ + ENET_SYMBOL_CREATE (symbol_, value_, update); \ + (context) -> symbols = symbol_ - (context); \ + }, \ + exclude (node -> value, after, before), \ + { \ + value_ = node->value + 1 + (code - after)/minimum; \ + under_ = code - (code - after)%minimum; \ + ENET_SYMBOL_CREATE (symbol_, value_, update); \ + node -> right = symbol_ - node; \ + }, \ + { \ + value_ = node->value - 1 - (after - before - code - 1)/minimum; \ + under_ = code - (after - before - code - 1)%minimum; \ + ENET_SYMBOL_CREATE (symbol_, value_, update); \ + node -> left = symbol_ - node; \ + }) \ + +#ifdef ENET_CONTEXT_EXCLUSION +typedef struct _ENetExclude +{ + enet_uint8 value; + enet_uint16 under; +} ENetExclude; + +#define ENET_CONTEXT_DECODE_EXCLUDE(context, total, minimum) \ +{ \ + enet_uint16 under = 0; \ + nextExclude = excludes; \ + ENET_CONTEXT_WALK (context, { \ + under += rangeCoder -> symbols [node -> parent].count + minimum; \ + nextExclude -> value = node -> value; \ + nextExclude -> under = under; \ + nextExclude ++; \ + }); \ + total -= under; \ +} + +#define ENET_CONTEXT_EXCLUDED(value_, after, before) \ +{ \ + size_t low = 0, high = nextExclude - excludes; \ + for(;;) \ + { \ + size_t mid = (low + high) >> 1; \ + const ENetExclude * exclude = & excludes [mid]; \ + if (value_ < exclude -> value) \ + { \ + if (low + 1 < high) \ + { \ + high = mid; \ + continue; \ + } \ + if (exclude > excludes) \ + after -= exclude [-1].under; \ + } \ + else \ + { \ + if (value_ > exclude -> value) \ + { \ + if (low + 1 < high) \ + { \ + low = mid; \ + continue; \ + } \ + } \ + else \ + before = 0; \ + after -= exclude -> under; \ + } \ + break; \ + } \ +} +#endif + +#define ENET_CONTEXT_NOT_EXCLUDED(value_, after, before) + +size_t +enet_range_coder_decompress (void * context, const enet_uint8 * inData, size_t inLimit, enet_uint8 * outData, size_t outLimit) +{ + ENetRangeCoder * rangeCoder = (ENetRangeCoder *) context; + enet_uint8 * outStart = outData, * outEnd = & outData [outLimit]; + const enet_uint8 * inEnd = & inData [inLimit]; + enet_uint32 decodeLow = 0, decodeCode = 0, decodeRange = ~0; + ENetSymbol * root; + enet_uint16 predicted = 0; + size_t order = 0, nextSymbol = 0; +#ifdef ENET_CONTEXT_EXCLUSION + ENetExclude excludes [256]; + ENetExclude * nextExclude = excludes; +#endif + + if (rangeCoder == NULL || inLimit <= 0) + return 0; + + ENET_CONTEXT_CREATE (root, ENET_CONTEXT_ESCAPE_MINIMUM, ENET_CONTEXT_SYMBOL_MINIMUM); + + ENET_RANGE_CODER_SEED; + + for (;;) + { + ENetSymbol * subcontext, * symbol, * patch; +#ifdef ENET_CONTEXT_EXCLUSION + const ENetSymbol * childContext = & emptyContext; +#endif + enet_uint8 value = 0; + enet_uint16 code, under, count, bottom, * parent = & predicted, total; + + for (subcontext = & rangeCoder -> symbols [predicted]; + subcontext != root; +#ifdef ENET_CONTEXT_EXCLUSION + childContext = subcontext, +#endif + subcontext = & rangeCoder -> symbols [subcontext -> parent]) + { + if (subcontext -> escapes <= 0) + continue; + total = subcontext -> total; +#ifdef ENET_CONTEXT_EXCLUSION + if (childContext -> total > 0) + ENET_CONTEXT_DECODE_EXCLUDE (childContext, total, 0); +#endif + if (subcontext -> escapes >= total) + continue; + code = ENET_RANGE_CODER_READ (total); + if (code < subcontext -> escapes) + { + ENET_RANGE_CODER_DECODE (0, subcontext -> escapes, total); + continue; + } + code -= subcontext -> escapes; +#ifdef ENET_CONTEXT_EXCLUSION + if (childContext -> total > 0) + { + ENET_CONTEXT_TRY_DECODE (subcontext, symbol, code, value, under, count, ENET_SUBCONTEXT_SYMBOL_DELTA, 0, ENET_CONTEXT_EXCLUDED); + } + else +#endif + { + ENET_CONTEXT_TRY_DECODE (subcontext, symbol, code, value, under, count, ENET_SUBCONTEXT_SYMBOL_DELTA, 0, ENET_CONTEXT_NOT_EXCLUDED); + } + bottom = symbol - rangeCoder -> symbols; + ENET_RANGE_CODER_DECODE (subcontext -> escapes + under, count, total); + subcontext -> total += ENET_SUBCONTEXT_SYMBOL_DELTA; + if (count > 0xFF - 2*ENET_SUBCONTEXT_SYMBOL_DELTA || subcontext -> total > ENET_RANGE_CODER_BOTTOM - 0x100) + ENET_CONTEXT_RESCALE (subcontext, 0); + goto patchContexts; + } + + total = root -> total; +#ifdef ENET_CONTEXT_EXCLUSION + if (childContext -> total > 0) + ENET_CONTEXT_DECODE_EXCLUDE (childContext, total, ENET_CONTEXT_SYMBOL_MINIMUM); +#endif + code = ENET_RANGE_CODER_READ (total); + if (code < root -> escapes) + { + ENET_RANGE_CODER_DECODE (0, root -> escapes, total); + break; + } + code -= root -> escapes; +#ifdef ENET_CONTEXT_EXCLUSION + if (childContext -> total > 0) + { + ENET_CONTEXT_ROOT_DECODE (root, symbol, code, value, under, count, ENET_CONTEXT_SYMBOL_DELTA, ENET_CONTEXT_SYMBOL_MINIMUM, ENET_CONTEXT_EXCLUDED); + } + else +#endif + { + ENET_CONTEXT_ROOT_DECODE (root, symbol, code, value, under, count, ENET_CONTEXT_SYMBOL_DELTA, ENET_CONTEXT_SYMBOL_MINIMUM, ENET_CONTEXT_NOT_EXCLUDED); + } + bottom = symbol - rangeCoder -> symbols; + ENET_RANGE_CODER_DECODE (root -> escapes + under, count, total); + root -> total += ENET_CONTEXT_SYMBOL_DELTA; + if (count > 0xFF - 2*ENET_CONTEXT_SYMBOL_DELTA + ENET_CONTEXT_SYMBOL_MINIMUM || root -> total > ENET_RANGE_CODER_BOTTOM - 0x100) + ENET_CONTEXT_RESCALE (root, ENET_CONTEXT_SYMBOL_MINIMUM); + + patchContexts: + for (patch = & rangeCoder -> symbols [predicted]; + patch != subcontext; + patch = & rangeCoder -> symbols [patch -> parent]) + { + ENET_CONTEXT_ENCODE (patch, symbol, value, under, count, ENET_SUBCONTEXT_SYMBOL_DELTA, 0); + * parent = symbol - rangeCoder -> symbols; + parent = & symbol -> parent; + if (count <= 0) + { + patch -> escapes += ENET_SUBCONTEXT_ESCAPE_DELTA; + patch -> total += ENET_SUBCONTEXT_ESCAPE_DELTA; + } + patch -> total += ENET_SUBCONTEXT_SYMBOL_DELTA; + if (count > 0xFF - 2*ENET_SUBCONTEXT_SYMBOL_DELTA || patch -> total > ENET_RANGE_CODER_BOTTOM - 0x100) + ENET_CONTEXT_RESCALE (patch, 0); + } + * parent = bottom; + + ENET_RANGE_CODER_OUTPUT (value); + + if (order >= ENET_SUBCONTEXT_ORDER) + predicted = rangeCoder -> symbols [predicted].parent; + else + order ++; + ENET_RANGE_CODER_FREE_SYMBOLS; + } + + return (size_t) (outData - outStart); +} + +/** Sets the packet compressor the host should use to the default range coder. + @param host host to enable the range coder for + @returns 0 on success, < 0 on failure +*/ +int +enet_host_compress_with_range_coder (ENetHost * host) +{ + ENetCompressor compressor; + memset (& compressor, 0, sizeof (compressor)); + compressor.context = enet_range_coder_create(); + if (compressor.context == NULL) + return -1; + compressor.compress = enet_range_coder_compress; + compressor.decompress = enet_range_coder_decompress; + compressor.destroy = enet_range_coder_destroy; + enet_host_compress (host, & compressor); + return 0; +} + + + |