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Decompile animReadBits

This commit is contained in:
Ryan Dwyer 2023-04-12 21:31:02 +10:00
parent 47add757e0
commit 4651682d76
1 changed files with 24 additions and 56 deletions
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80
src/lib/anim.c
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@ -363,76 +363,44 @@ void animLoadHeader(s16 animnum)
}
}
#if MATCHING
GLOBAL_ASM(
glabel animReadBits
/* 23f50: 30cf0007 */ andi $t7,$a2,0x7
/* 23f54: 24180008 */ addiu $t8,$zero,0x8
/* 23f58: 030f4023 */ subu $t0,$t8,$t7
/* 23f5c: 30a900ff */ andi $t1,$a1,0xff
/* 23f60: 311900ff */ andi $t9,$t0,0xff
/* 23f64: 000610c2 */ srl $v0,$a2,0x3
/* 23f68: 0139082a */ slt $at,$t1,$t9
/* 23f6c: afa50004 */ sw $a1,0x4($sp)
/* 23f70: 00001825 */ or $v1,$zero,$zero
/* 23f74: 00822021 */ addu $a0,$a0,$v0
/* 23f78: 1420000e */ bnez $at,.L00023fb4
/* 23f7c: 310700ff */ andi $a3,$t0,0xff
.L00023f80:
/* 23f80: 908b0000 */ lbu $t3,0x0($a0)
/* 23f84: 240c0001 */ addiu $t4,$zero,0x1
/* 23f88: 01272823 */ subu $a1,$t1,$a3
/* 23f8c: 00ec6804 */ sllv $t5,$t4,$a3
/* 23f90: 30a900ff */ andi $t1,$a1,0xff
/* 23f94: 25aeffff */ addiu $t6,$t5,-1
/* 23f98: 016e7824 */ and $t7,$t3,$t6
/* 23f9c: 012fc004 */ sllv $t8,$t7,$t1
/* 23fa0: 29210008 */ slti $at,$t1,0x8
/* 23fa4: 00781825 */ or $v1,$v1,$t8
/* 23fa8: 24840001 */ addiu $a0,$a0,0x1
/* 23fac: 1020fff4 */ beqz $at,.L00023f80
/* 23fb0: 24070008 */ addiu $a3,$zero,0x8
.L00023fb4:
/* 23fb4: 19200008 */ blez $t1,.L00023fd8
/* 23fb8: 00e95023 */ subu $t2,$a3,$t1
/* 23fbc: 90990000 */ lbu $t9,0x0($a0)
/* 23fc0: 240d0001 */ addiu $t5,$zero,0x1
/* 23fc4: 012d5804 */ sllv $t3,$t5,$t1
/* 23fc8: 256effff */ addiu $t6,$t3,-1
/* 23fcc: 01596007 */ srav $t4,$t9,$t2
/* 23fd0: 018e7824 */ and $t7,$t4,$t6
/* 23fd4: 006f1825 */ or $v1,$v1,$t7
.L00023fd8:
/* 23fd8: 03e00008 */ jr $ra
/* 23fdc: 00601025 */ or $v0,$v1,$zero
);
#else
// Mismatch: regalloc
s32 animReadBits(u8 *ptr, u8 readbitlen, u32 bitoffset)
/**
* Read a number of bits from the given ptr and return it as an integer.
*
* remainingbits in the number of bits to read.
* bitoffset is the starting bit offset relative to ptr.
*/
s32 animReadBits(u8 *ptr, u8 remainingbits, u32 bitoffset)
{
u32 result = 0;
u32 mask;
u8 numbitsthisbyte;
u32 tmp;
result *= bitoffset / 8;
// Move ptr forward past all the bytes that should be fully skipped
ptr += bitoffset / 8;
numbitsthisbyte = 8 - (bitoffset % 8);
while (readbitlen >= numbitsthisbyte) {
readbitlen -= numbitsthisbyte;
result |= (*ptr & ((1 << numbitsthisbyte) - 1)) << readbitlen;
// Calculate the number of bits to read in the first byte
bitoffset %= 8;
numbitsthisbyte = 8 - bitoffset;
// Iterate bytes, except for the last if it's a partial read
while (remainingbits >= numbitsthisbyte) {
remainingbits -= numbitsthisbyte;
mask = (1 << numbitsthisbyte) - 1;
result |= (*ptr & mask) << remainingbits;
ptr++;
numbitsthisbyte = 8;
}
if (readbitlen > 0) {
result |= (*ptr >> (numbitsthisbyte - readbitlen)) & ((1 << readbitlen) - 1);
// Read bits from the final byte if it's partial read
if (remainingbits > 0) {
mask = (1 << remainingbits) - 1;
result |= (*ptr >> (numbitsthisbyte - remainingbits)) & mask;
}
if (bitoffset / 8);
return result;
}
#endif
s32 animReadSignedShort(u8 *ptr, u8 readbitlen, s32 bitoffset)
{