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Implement Huffman

This commit is contained in:
Jeffrey Pfau 2013-10-12 13:32:23 -07:00
parent 973abb7b94
commit d8778cf516
1 changed files with 92 additions and 0 deletions
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92
src/gba/gba-bios.c
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@ -8,6 +8,7 @@
#include <stdlib.h>
static void _unLz77(struct GBAMemory* memory, uint32_t source, uint8_t* dest);
static void _unHuffman(struct GBAMemory* memory, uint32_t source, uint32_t* dest);
static void _unRl(struct GBAMemory* memory, uint32_t source, uint8_t* dest);
static void _RegisterRamReset(struct GBA* gba) {
@ -259,6 +260,22 @@ void GBASwi16(struct ARMBoard* board, int immediate) {
break;
}
break;
case 0x13:
switch (gba->cpu.gprs[1] >> BASE_OFFSET) {
case REGION_WORKING_RAM:
_unHuffman(&gba->memory, gba->cpu.gprs[0], &((uint32_t*) gba->memory.wram)[(gba->cpu.gprs[1] & (SIZE_WORKING_RAM - 3))]);
break;
case REGION_WORKING_IRAM:
_unHuffman(&gba->memory, gba->cpu.gprs[0], &((uint32_t*) gba->memory.iwram)[(gba->cpu.gprs[1] & (SIZE_WORKING_IRAM - 3))]);
break;
case REGION_VRAM:
_unHuffman(&gba->memory, gba->cpu.gprs[0], &((uint32_t*) gba->video.renderer->vram)[(gba->cpu.gprs[1] & 0x0001FFFC)]);
break;
default:
GBALog(gba, GBA_LOG_WARN, "Bad Huffman destination");
break;
}
break;
case 0x14:
case 0x15:
switch (gba->cpu.gprs[1] >> BASE_OFFSET) {
@ -327,6 +344,81 @@ static void _unLz77(struct GBAMemory* memory, uint32_t source, uint8_t* dest) {
}
}
static void _unHuffman(struct GBAMemory* memory, uint32_t source, uint32_t* dest) {
source = source & 0xFFFFFFFC;
uint32_t header = memory->d.load32(&memory->d, source, 0);
int remaining = header >> 8;
int bits = header & 0xF;
if (32 % bits) {
GBALog(memory->p, GBA_LOG_STUB, "Unimplemented unaligned Huffman");
return;
}
int padding = (4 - remaining) & 0x3;
remaining &= 0xFFFFFFFC;
// We assume the signature byte (0x20) is correct
//var tree = [];
int treesize = (memory->d.load8(&memory->d, source + 4, 0) << 1) + 1;
int block = 0;
uint32_t treeBase = source + 5;
uint32_t sPointer = source + 5 + treesize;
uint32_t* dPointer = dest;
uint32_t nPointer = treeBase;
union HuffmanNode {
struct {
unsigned offset : 6;
unsigned rTerm : 1;
unsigned lTerm : 1;
};
uint8_t packed;
} node;
int bitsRemaining;
int readBits;
int bitsSeen = 0;
node.packed = memory->d.load8(&memory->d, nPointer, 0);
while (remaining > 0) {
uint32_t bitstream = memory->d.load32(&memory->d, sPointer, 0);
sPointer += 4;
for (bitsRemaining = 32; bitsRemaining > 0; --bitsRemaining, bitstream <<= 1) {
uint32_t next = (nPointer & ~1) + node.offset * 2 + 2;
if (bitstream & 0x80000000) {
// Go right
if (node.rTerm) {
readBits = memory->d.load8(&memory->d, next + 1, 0);
} else {
nPointer = next + 1;
node.packed = memory->d.load8(&memory->d, nPointer, 0);
continue;
}
} else {
// Go left
if (node.lTerm) {
readBits = memory->d.load8(&memory->d, next, 0);
} else {
nPointer = next;
node.packed = memory->d.load8(&memory->d, nPointer, 0);
continue;
}
}
block |= (readBits & ((1 << bits) - 1)) << bitsSeen;
bitsSeen += bits;
nPointer = treeBase;
node.packed = memory->d.load8(&memory->d, nPointer, 0);
if (bitsSeen == 32) {
bitsSeen = 0;
*dPointer = block;
++dPointer;
remaining -= 4;
block = 0;
}
}
}
if (padding) {
*dPointer = block;
}
}
static void _unRl(struct GBAMemory* memory, uint32_t source, uint8_t* dest) {
source = source & 0xFFFFFFFC;
int remaining = (memory->d.load32(&memory->d, source, 0) & 0xFFFFFF00) >> 8;