What the original function actually looked like: f32 atan2(f32 startX, f32 startZ, f32 endX, f32 endZ) {
f32 xDiff = endX - startX;
f32 zDiff = endZ - startZ;
f32 absXDiff = fabsf(xDiff);
f32 absZDiff = fabsf(zDiff);
f32 ret;
if (absZDiff < absXDiff) {
ret = (absZDiff / absXDiff) * 45.0f;
ret *= sAtanFactors[round(2.0f * ret)];
if (xDiff >= 0.0f) {
if (zDiff >= 0.0f) {
return ret + 90.0f;
} else {
return 90.0f - ret;
}
}
if (zDiff >= 0.0f) {
return 270.0f - ret;
} else {
return ret + 270.0f;
}
} else {
if (absZDiff == 0.0f) {
return 0.0f;
}
ret = (absXDiff / absZDiff) * 45.0f;
ret *= sAtanFactors[round(2.0f * ret)];
if (zDiff >= 0.0f) {
if (xDiff >= 0.0f) {
return 180.0f - ret;
} else {
return ret + 180.0f;
}
} else if (!(xDiff >= 0.0f)) {
return 360.0f - ret;
}
}
return ret;
}
#include <math.h>
// External lookup table for precomputed coefficients (likely generated during compilation)
extern float D_80074414[];
float atan2_custom(float x1, float y1, float x2, float y2) {
float dx = x2 - x1;
float dy = y2 - y1;
float abs_dx = fabsf(dx);
float abs_dy = fabsf(dy);
float ratio, angle;
int index;
if (abs_dy < abs_dx) {
// Case 1: |dy| < |dx|, use dy/dx ratio
ratio = abs_dy / abs_dx * 45.0f;
index = round(ratio * 2.0f);
angle = ratio * D_80074414[index];
// Adjust angle based on quadrant
if (dx >= 0.0f) {
angle = (dy >= 0.0f) ? (90.0f + angle) : (90.0f - angle);
} else {
angle = (dy >= 0.0f) ? (270.0f - angle) : (270.0f + angle);
}
} else {
// Case 2: |dx| <= |dy|, use dx/dy ratio
if (abs_dy == 0.0f) return 0.0f; // Avoid division by zero
ratio = abs_dx / abs_dy * 45.0f;
index = round(ratio * 2.0f);
angle = ratio * D_80074414[index];
// Adjust angle based on quadrant
if (dy >= 0.0f) {
angle = (dx >= 0.0f) ? (180.0f - angle) : (180.0f + angle);
} else {
angle = (dx >= 0.0f) ? (360.0f - angle) : (360.0f + angle);
}
}
return angle;
}
The MIPS context that r1 was given: glabel atan2
/* 5080 80029C80 44863000 */ mtc1 $a2, $f6
/* 5084 80029C84 27BDFFC8 */ addiu $sp, $sp, -0x38
/* 5088 80029C88 F7BA0030 */ sdc1 $f26, 0x30($sp)
/* 508C 80029C8C 460C3681 */ sub.s $f26, $f6, $f12
/* 5090 80029C90 44873000 */ mtc1 $a3, $f6
/* 5094 80029C94 AFBF0010 */ sw $ra, 0x10($sp)
/* 5098 80029C98 F7B80028 */ sdc1 $f24, 0x28($sp)
/* 509C 80029C9C 460E3601 */ sub.s $f24, $f6, $f14
/* 50A0 80029CA0 F7B60020 */ sdc1 $f22, 0x20($sp)
/* 50A4 80029CA4 F7B40018 */ sdc1 $f20, 0x18($sp)
/* 50A8 80029CA8 4600D105 */ abs.s $f4, $f26
/* 50AC 80029CAC 4600C005 */ abs.s $f0, $f24
/* 50B0 80029CB0 4604003C */ c.lt.s $f0, $f4
/* 50B4 80029CB4 00000000 */ nop
/* 50B8 80029CB8 45000029 */ bc1f .L80029D60
/* 50BC 80029CBC 00000000 */ nop
/* 50C0 80029CC0 3C014234 */ lui $at, (0x42340000 >> 16)
/* 50C4 80029CC4 44811000 */ mtc1 $at, $f2
/* 50C8 80029CC8 46040003 */ div.s $f0, $f0, $f4
/* 50CC 80029CCC 46020502 */ mul.s $f20, $f0, $f2
/* 50D0 80029CD0 00000000 */ nop
/* 50D4 80029CD4 0C00A6B1 */ jal round
/* 50D8 80029CD8 4614A300 */ add.s $f12, $f20, $f20
/* 50DC 80029CDC 00021080 */ sll $v0, $v0, 2
/* 50E0 80029CE0 3C018007 */ lui $at, %hi(D_80074414)
/* 50E4 80029CE4 00220821 */ addu $at, $at, $v0
/* 50E8 80029CE8 C4204414 */ lwc1 $f0, %lo(D_80074414)($at)
/* 50EC 80029CEC 4600A502 */ mul.s $f20, $f20, $f0
/* 50F0 80029CF0 00000000 */ nop
/* 50F4 80029CF4 44800000 */ mtc1 $zero, $f0
/* 50F8 80029CF8 00000000 */ nop
/* 50FC 80029CFC 461A003E */ c.le.s $f0, $f26
/* 5100 80029D00 00000000 */ nop
/* 5104 80029D04 4500000D */ bc1f .L80029D3C
/* 5108 80029D08 00000000 */ nop
/* 510C 80029D0C 4618003E */ c.le.s $f0, $f24
/* 5110 80029D10 00000000 */ nop
/* 5114 80029D14 45000005 */ bc1f .L80029D2C
/* 5118 80029D18 00000000 */ nop
/* 511C 80029D1C 3C0142B4 */ lui $at, (0x42B40000 >> 16)
/* 5120 80029D20 44810000 */ mtc1 $at, $f0
/* 5124 80029D24 0800A781 */ j .L80029E04
/* 5128 80029D28 4600A000 */ add.s $f0, $f20, $f0
.L80029D2C:
/* 512C 80029D2C 3C0142B4 */ lui $at, (0x42B40000 >> 16)
/* 5130 80029D30 44810000 */ mtc1 $at, $f0
/* 5134 80029D34 0800A781 */ j .L80029E04
/* 5138 80029D38 46140001 */ sub.s $f0, $f0, $f20
.L80029D3C:
/* 513C 80029D3C 4618003E */ c.le.s $f0, $f24
/* 5140 80029D40 3C014387 */ lui $at, (0x43870000 >> 16)
/* 5144 80029D44 44810000 */ mtc1 $at, $f0
/* 5148 80029D48 4503002E */ bc1tl .L80029E04
/* 514C 80029D4C 46140001 */ sub.s $f0, $f0, $f20
/* 5150 80029D50 3C014387 */ lui $at, (0x43870000 >> 16)
/* 5154 80029D54 44810000 */ mtc1 $at, $f0
/* 5158 80029D58 0800A781 */ j .L80029E04
/* 515C 80029D5C 4600A000 */ add.s $f0, $f20, $f0
.L80029D60:
/* 5160 80029D60 4480B000 */ mtc1 $zero, $f22
/* 5164 80029D64 00000000 */ nop
/* 5168 80029D68 46160032 */ c.eq.s $f0, $f22
/* 516C 80029D6C 00000000 */ nop
/* 5170 80029D70 45020003 */ bc1fl .L80029D80
/* 5174 80029D74 46002003 */ div.s $f0, $f4, $f0
/* 5178 80029D78 0800A781 */ j .L80029E04
/* 517C 80029D7C 4600B006 */ mov.s $f0, $f22
.L80029D80:
/* 5180 80029D80 3C014234 */ lui $at, (0x42340000 >> 16)
/* 5184 80029D84 44811000 */ mtc1 $at, $f2
/* 5188 80029D88 00000000 */ nop
/* 518C 80029D8C 46020502 */ mul.s $f20, $f0, $f2
/* 5190 80029D90 00000000 */ nop
/* 5194 80029D94 0C00A6B1 */ jal round
/* 5198 80029D98 4614A300 */ add.s $f12, $f20, $f20
/* 519C 80029D9C 00021080 */ sll $v0, $v0, 2
/* 51A0 80029DA0 3C018007 */ lui $at, %hi(D_80074414)
/* 51A4 80029DA4 00220821 */ addu $at, $at, $v0
/* 51A8 80029DA8 C4204414 */ lwc1 $f0, %lo(D_80074414)($at)
/* 51AC 80029DAC 4618B03E */ c.le.s $f22, $f24
/* 51B0 80029DB0 4600A502 */ mul.s $f20, $f20, $f0
/* 51B4 80029DB4 00000000 */ nop
/* 51B8 80029DB8 4500000A */ bc1f .L80029DE4
/* 51BC 80029DBC 00000000 */ nop
/* 51C0 80029DC0 461AB03E */ c.le.s $f22, $f26
/* 51C4 80029DC4 3C014334 */ lui $at, (0x43340000 >> 16)
/* 51C8 80029DC8 44810000 */ mtc1 $at, $f0
/* 51CC 80029DCC 4503000D */ bc1tl .L80029E04
/* 51D0 80029DD0 46140001 */ sub.s $f0, $f0, $f20
/* 51D4 80029DD4 3C014334 */ lui $at, (0x43340000 >> 16)
/* 51D8 80029DD8 44810000 */ mtc1 $at, $f0
/* 51DC 80029DDC 0800A781 */ j .L80029E04
/* 51E0 80029DE0 4600A000 */ add.s $f0, $f20, $f0
.L80029DE4:
/* 51E4 80029DE4 461AB03E */ c.le.s $f22, $f26
/* 51E8 80029DE8 00000000 */ nop
/* 51EC 80029DEC 45010005 */ bc1t .L80029E04
/* 51F0 80029DF0 4600A006 */ mov.s $f0, $f20
/* 51F4 80029DF4 3C0143B4 */ lui $at, (0x43B40000 >> 16)
/* 51F8 80029DF8 44810000 */ mtc1 $at, $f0
/* 51FC 80029DFC 00000000 */ nop
/* 5200 80029E00 46140001 */ sub.s $f0, $f0, $f20
.L80029E04:
/* 5204 80029E04 8FBF0010 */ lw $ra, 0x10($sp)
/* 5208 80029E08 D7BA0030 */ ldc1 $f26, 0x30($sp)
/* 520C 80029E0C D7B80028 */ ldc1 $f24, 0x28($sp)
/* 5210 80029E10 D7B60020 */ ldc1 $f22, 0x20($sp)
/* 5214 80029E14 D7B40018 */ ldc1 $f20, 0x18($sp)
/* 5218 80029E18 03E00008 */ jr $ra
/* 521C 80029E1C 27BD0038 */ addiu $sp, $sp, 0x38
