Skip to content
Permalink
Browse files
GBA BIOS: Add timings for HLE BIOS math functions (fixes #1396)
  • Loading branch information
endrift committed Apr 27, 2019
1 parent 6af4dde commit 223be49e7845327997a5258338cf6eb6190b475f
Show file tree
Hide file tree
Showing 2 changed files with 100 additions and 11 deletions.
@@ -42,6 +42,7 @@ Misc:
- Core: Add keysRead callback
- Vita: Improved frame drawing speed
- Qt: Cap window size on start to monitor size
- GBA BIOS: Add timings for HLE BIOS math functions (fixes mgba.io/i/1396)

0.7.1: (2019-02-24)
Bugfixes:
@@ -10,6 +10,7 @@
#include <mgba/internal/gba/gba.h>
#include <mgba/internal/gba/io.h>
#include <mgba/internal/gba/memory.h>
#include <mgba-util/math.h>

const uint32_t GBA_BIOS_CHECKSUM = 0xBAAE187F;
const uint32_t GBA_DS_BIOS_CHECKSUM = 0xBAAE1880;
@@ -22,6 +23,18 @@ static void _unRl(struct GBA* gba, int width);
static void _unFilter(struct GBA* gba, int inwidth, int outwidth);
static void _unBitPack(struct GBA* gba);

static int _mulWait(int32_t r) {
if ((r & 0xFFFFFF00) == 0xFFFFFF00 || !(r & 0xFFFFFF00)) {
return 1;
} else if ((r & 0xFFFF0000) == 0xFFFF0000 || !(r & 0xFFFF0000)) {
return 2;
} else if ((r & 0xFF000000) == 0xFF000000 || !(r & 0xFF000000)) {
return 3;
} else {
return 4;
}
}

static void _SoftReset(struct GBA* gba) {
struct ARMCore* cpu = gba->cpu;
ARMSetPrivilegeMode(cpu, MODE_IRQ);
@@ -273,27 +286,42 @@ static void _Div(struct GBA* gba, int32_t num, int32_t denom) {
cpu->gprs[1] = 0;
cpu->gprs[3] = INT32_MIN;
}
int loops = clz32(denom) - clz32(num);
if (loops < 1) {
loops = 1;
}
cpu->cycles += 4 /* prologue */ + 13 * loops + 7 /* epilogue */;
}

static int16_t _ArcTan(int32_t i, int32_t* r1, int32_t* r3) {
static int16_t _ArcTan(int32_t i, int32_t* r1, int32_t* r3, int32_t* cycles) {
int currentCycles = 37;
currentCycles += _mulWait(i * i);
int32_t a = -((i * i) >> 14);
currentCycles += _mulWait(0xA9 * a);
int32_t b = ((0xA9 * a) >> 14) + 0x390;
currentCycles += _mulWait(b * a);
b = ((b * a) >> 14) + 0x91C;
currentCycles += _mulWait(b * a);
b = ((b * a) >> 14) + 0xFB6;
currentCycles += _mulWait(b * a);
b = ((b * a) >> 14) + 0x16AA;
currentCycles += _mulWait(b * a);
b = ((b * a) >> 14) + 0x2081;
currentCycles += _mulWait(b * a);
b = ((b * a) >> 14) + 0x3651;
currentCycles += _mulWait(b * a);
b = ((b * a) >> 14) + 0xA2F9;
if (r1) {
*r1 = a;
}
if (r3) {
*r3 = b;
}
*cycles += currentCycles;
return (i * b) >> 16;
}

static int16_t _ArcTan2(int32_t x, int32_t y, int32_t* r1) {
static int16_t _ArcTan2(int32_t x, int32_t y, int32_t* r1, int32_t* cycles) {
if (!y) {
if (x >= 0) {
return 0;
@@ -309,24 +337,77 @@ static int16_t _ArcTan2(int32_t x, int32_t y, int32_t* r1) {
if (y >= 0) {
if (x >= 0) {
if (x >= y) {
return _ArcTan((y << 14) / x, r1, NULL);
return _ArcTan((y << 14) / x, r1, NULL, cycles);
}
} else if (-x >= y) {
return _ArcTan((y << 14) / x, r1, NULL) + 0x8000;
return _ArcTan((y << 14) / x, r1, NULL, cycles) + 0x8000;
}
return 0x4000 - _ArcTan((x << 14) / y, r1, NULL);
return 0x4000 - _ArcTan((x << 14) / y, r1, NULL, cycles);
} else {
if (x <= 0) {
if (-x > -y) {
return _ArcTan((y << 14) / x, r1, NULL) + 0x8000;
return _ArcTan((y << 14) / x, r1, NULL, cycles) + 0x8000;
}
} else if (x >= -y) {
return _ArcTan((y << 14) / x, r1, NULL) + 0x10000;
return _ArcTan((y << 14) / x, r1, NULL, cycles) + 0x10000;
}
return 0xC000 - _ArcTan((x << 14) / y, r1, NULL);
return 0xC000 - _ArcTan((x << 14) / y, r1, NULL, cycles);
}
}

static int32_t _Sqrt(uint32_t x, int32_t* cycles) {
if (!x) {
*cycles += 53;
return 0;
}
int32_t currentCycles = 15;
uint32_t lower;
uint32_t upper = x;
uint32_t bound = 1;
while (bound < upper) {
upper >>= 1;
bound <<= 1;
currentCycles += 6;
}
while (true) {
currentCycles += 6;
upper = x;
uint32_t accum = 0;
lower = bound;
while (true) {
currentCycles += 5;
uint32_t oldLower = lower;
if (lower <= upper >> 1) {
lower <<= 1;
}
if (oldLower >= upper >> 1) {
break;
}
}
while (true) {
currentCycles += 8;
accum <<= 1;
if (upper >= lower) {
++accum;
upper -= lower;
}
if (lower == bound) {
break;
}
lower >>= 1;
}
uint32_t oldBound = bound;
bound += accum;
bound >>= 1;
if (bound >= oldBound) {
bound = oldBound;
break;
}
}
*cycles += currentCycles;
return bound;
}

void GBASwi16(struct ARMCore* cpu, int immediate) {
struct GBA* gba = (struct GBA*) cpu->master;
mLOG(GBA_BIOS, DEBUG, "SWI: %02X r0: %08X r1: %08X r2: %08X r3: %08X",
@@ -369,13 +450,13 @@ void GBASwi16(struct ARMCore* cpu, int immediate) {
_Div(gba, cpu->gprs[1], cpu->gprs[0]);
break;
case 0x8:
cpu->gprs[0] = sqrt((uint32_t) cpu->gprs[0]);
cpu->gprs[0] = _Sqrt(cpu->gprs[0], &cpu->cycles);
break;
case 0x9:
cpu->gprs[0] = _ArcTan(cpu->gprs[0], &cpu->gprs[1], &cpu->gprs[3]);
cpu->gprs[0] = _ArcTan(cpu->gprs[0], &cpu->gprs[1], &cpu->gprs[3], &cpu->cycles);
break;
case 0xA:
cpu->gprs[0] = (uint16_t) _ArcTan2(cpu->gprs[0], cpu->gprs[1], &cpu->gprs[1]);
cpu->gprs[0] = (uint16_t) _ArcTan2(cpu->gprs[0], cpu->gprs[1], &cpu->gprs[1], &cpu->cycles);
cpu->gprs[3] = 0x170;
break;
case 0xB:
@@ -497,6 +578,13 @@ void GBASwi16(struct ARMCore* cpu, int immediate) {
default:
mLOG(GBA_BIOS, STUB, "Stub software interrupt: %02X", immediate);
}
gba->cpu->cycles += 45 + cpu->memory.activeNonseqCycles16 /* 8 bit load for SWI # */;
// Return cycles
if (gba->cpu->executionMode == MODE_ARM) {
gba->cpu->cycles += cpu->memory.activeNonseqCycles32 + cpu->memory.activeSeqCycles32;
} else {
gba->cpu->cycles += cpu->memory.activeNonseqCycles16 + cpu->memory.activeSeqCycles16;
}
gba->memory.biosPrefetch = 0xE3A02004;
}

0 comments on commit 223be49

Please sign in to comment.