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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 a = -((i * i) >> 14);
int32_t b = ((0xA9 * a) >> 14) + 0x390; int32_t b = ((0xA9 * a) >> 14) + 0x390;
b = ((b * a) >> 14) + 0x91C; 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) + 0x2081;
b = ((b * a) >> 14) + 0x3651; b = ((b * a) >> 14) + 0x3651;
b = ((b * a) >> 14) + 0xA2F9; b = ((b * a) >> 14) + 0xA2F9;
if (r1) {
*r1 = a;
}
if (r3) {
*r3 = b;
}
return (i * b) >> 16; 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 (!y) {
if (x >= 0) { if (x >= 0) {
return 0; return 0;
@ -299,21 +305,21 @@ static int16_t _ArcTan2(int32_t x, int32_t y) {
if (y >= 0) { if (y >= 0) {
if (x >= 0) { if (x >= 0) {
if (x >= y) { if (x >= y) {
return _ArcTan((y << 14) / x); return _ArcTan((y << 14) / x, r1, NULL);
} }
} else if (-x >= y) { } 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 { } else {
if (x <= 0) { if (x <= 0) {
if (-x > -y) { if (-x > -y) {
return _ArcTan((y << 14) / x) + 0x8000; return _ArcTan((y << 14) / x, r1, NULL) + 0x8000;
} }
} else if (x >= -y) { } 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]); cpu->gprs[0] = sqrt((uint32_t) cpu->gprs[0]);
break; break;
case 0x9: case 0x9:
cpu->gprs[0] = _ArcTan(cpu->gprs[0]); cpu->gprs[0] = _ArcTan(cpu->gprs[0], &cpu->gprs[1], &cpu->gprs[3]);
break; break;
case 0xA: 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; cpu->gprs[3] = 0x170;
break; break;
case 0xB: case 0xB: