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GBA BIOS: ArcTan/ArcTan2 fixes for HLE bios 

Fix ArcTan and ArcTan2 based on mgba's hle bios fixes
- References:
- 14dc01409c (diff-8f06a143a9fd912c83209f935d3aca25)
- b154457857 (diff-8f06a143a9fd912c83209f935d3aca25)
This commit is contained in:
negativeExponent 2020-08-12 21:06:57 +08:00
parent 364a182968
commit 2f9933ae49
1 changed files with 12 additions and 4 deletions
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16
src/gba/bios.cpp
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@ -42,6 +42,11 @@ int16_t sineTable[256] = {
(int16_t)0xF384, (int16_t)0xF50F, (int16_t)0xF69C, (int16_t)0xF82B, (int16_t)0xF9BB, (int16_t)0xFB4B, (int16_t)0xFCDD, (int16_t)0xFE6E
};
// 2020-08-12 - negativeExponent
// Fix ArcTan and ArcTan2 based on mgba's hle bios fixes
// https://github.com/mgba-emu/mgba/commit/14dc01409c9e971ea0697f5017b45d0db6a7faf5#diff-8f06a143a9fd912c83209f935d3aca25
// https://github.com/mgba-emu/mgba/commit/b154457857d3367a4c0196a4abadeeb6c850ffdf#diff-8f06a143a9fd912c83209f935d3aca25
void BIOS_ArcTan()
{
#ifdef GBA_LOGGING
@ -52,7 +57,8 @@ void BIOS_ArcTan()
}
#endif
int32_t a = -(((int32_t)(reg[0].I * reg[0].I)) >> 14);
int32_t i = reg[0].I;
int32_t a = -((i * i) >> 14);
int32_t b = ((0xA9 * a) >> 14) + 0x390;
b = ((b * a) >> 14) + 0x91C;
b = ((b * a) >> 14) + 0xFB6;
@ -60,8 +66,9 @@ void BIOS_ArcTan()
b = ((b * a) >> 14) + 0x2081;
b = ((b * a) >> 14) + 0x3651;
b = ((b * a) >> 14) + 0xA2F9;
a = ((int32_t)reg[0].I * b) >> 16;
reg[0].I = a;
reg[0].I = (i * b) >> 16;
reg[1].I = a;
reg[3].I = b;
#ifdef GBA_LOGGING
if (systemVerbose & VERBOSE_SWI) {
@ -84,7 +91,7 @@ void BIOS_ArcTan2()
int32_t x = reg[0].I;
int32_t y = reg[1].I;
uint32_t res = 0;
int32_t res = 0;
if (y == 0) {
res = ((x >> 16) & 0x8000);
} else {
@ -109,6 +116,7 @@ void BIOS_ArcTan2()
}
}
reg[0].I = res;
reg[3].I = 0x170;
#ifdef GBA_LOGGING
if (systemVerbose & VERBOSE_SWI) {