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GBA BIOS: ArcTan/ArcTan2 residual register state

This commit is contained in:
Vicki Pfau 2017-04-21 00:01:35 -07:00
parent b154457857
commit 14dc01409c
1 changed files with 16 additions and 10 deletions
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26
src/gba/bios.c
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@ -271,7 +271,7 @@ static void _Div(struct GBA* gba, int32_t num, int32_t denom) {
}
}
static int16_t _ArcTan(int32_t i) {
static int16_t _ArcTan(int32_t i, int32_t* r1, int32_t* r3) {
int32_t a = -((i * i) >> 14);
int32_t b = ((0xA9 * a) >> 14) + 0x390;
b = ((b * a) >> 14) + 0x91C;
@ -280,10 +280,16 @@ static int16_t _ArcTan(int32_t i) {
b = ((b * a) >> 14) + 0x2081;
b = ((b * a) >> 14) + 0x3651;
b = ((b * a) >> 14) + 0xA2F9;
if (r1) {
*r1 = a;
}
if (r3) {
*r3 = b;
}
return (i * b) >> 16;
}
static int16_t _ArcTan2(int32_t x, int32_t y) {
static int16_t _ArcTan2(int32_t x, int32_t y, int32_t* r1) {
if (!y) {
if (x >= 0) {
return 0;
@ -299,21 +305,21 @@ static int16_t _ArcTan2(int32_t x, int32_t y) {
if (y >= 0) {
if (x >= 0) {
if (x >= y) {
return _ArcTan((y << 14) / x);
return _ArcTan((y << 14) / x, r1, NULL);
}
} else if (-x >= y) {
return _ArcTan((y << 14) / x) + 0x8000;
return _ArcTan((y << 14) / x, r1, NULL) + 0x8000;
}
return 0x4000 - _ArcTan((x << 14) / y);
return 0x4000 - _ArcTan((x << 14) / y, r1, NULL);
} else {
if (x <= 0) {
if (-x > -y) {
return _ArcTan((y << 14) / x) + 0x8000;
return _ArcTan((y << 14) / x, r1, NULL) + 0x8000;
}
} else if (x >= -y) {
return _ArcTan((y << 14) / x) + 0x10000;
return _ArcTan((y << 14) / x, r1, NULL) + 0x10000;
}
return 0xC000 - _ArcTan((x << 14) / y);
return 0xC000 - _ArcTan((x << 14) / y, r1, NULL);
}
}
@ -356,10 +362,10 @@ void GBASwi16(struct ARMCore* cpu, int immediate) {
cpu->gprs[0] = sqrt((uint32_t) cpu->gprs[0]);
break;
case 0x9:
cpu->gprs[0] = _ArcTan(cpu->gprs[0]);
cpu->gprs[0] = _ArcTan(cpu->gprs[0], &cpu->gprs[1], &cpu->gprs[3]);
break;
case 0xA:
cpu->gprs[0] = (uint16_t) _ArcTan2(cpu->gprs[0], cpu->gprs[1]);
cpu->gprs[0] = (uint16_t) _ArcTan2(cpu->gprs[0], cpu->gprs[1], &cpu->gprs[1]);
cpu->gprs[3] = 0x170;
break;
case 0xB: