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libgambatte/cpu: less magic HF2 constants

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This commit is contained in:
sinamas 2013-02-25 22:44:19 +01:00
parent f70cf21f38
commit e43c5b07f6
1 changed files with 35 additions and 36 deletions
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71
libgambatte/src/cpu.cpp
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@ -53,33 +53,32 @@ long CPU::runFor(const unsigned long cycles) {
return csb; return csb;
} }
// (HF2 & 0x200) == true means HF is set. enum { HF2_HCF = 0x200, HF2_SUBF = 0x400, HF2_INCF = 0x800 };
// (HF2 & 0x400) marks the subtract flag.
// (HF2 & 0x800) is set for inc/dec.
// (HF2 & 0x100) is set if there's a carry to add.
static void calcHF(const unsigned HF1, unsigned& HF2) {
unsigned arg1 = HF1 & 0xF;
unsigned arg2 = (HF2 & 0xF) + (HF2 >> 8 & 1);
if (HF2 & 0x800) { static unsigned updateHF2FromHF1(const unsigned HF1, unsigned HF2) {
arg1 = arg2; unsigned lhs = HF1 & 0xF;
arg2 = 1; unsigned rhs = (HF2 & 0xF) + (HF2 >> 8 & 1);
if (HF2 & HF2_INCF) {
lhs = rhs;
rhs = 1;
} }
if (HF2 & 0x400) unsigned res = HF2 & HF2_SUBF
arg1 -= arg2; ? lhs - rhs
else : (lhs + rhs) << 5;
arg1 = (arg1 + arg2) << 5;
HF2 |= arg1 & 0x200; HF2 |= res & HF2_HCF;
return HF2;
} }
static inline unsigned toF(unsigned HF2, unsigned CF, unsigned ZF) { static inline unsigned toF(unsigned HF2, unsigned CF, unsigned ZF) {
return ((HF2 & 0x600) | (CF & 0x100)) >> 4 | (ZF & 0xFF ? 0 : 0x80); return ((HF2 & (HF2_SUBF | HF2_HCF)) | (CF & 0x100)) >> 4
| (ZF & 0xFF ? 0 : 0x80);
} }
static inline unsigned zfFromF(unsigned f) { return ~f & 0x80; } static inline unsigned zfFromF(unsigned f) { return ~f & 0x80; }
static inline unsigned hf2FromF(unsigned f) { return f << 4 & 0x600; } static inline unsigned hf2FromF(unsigned f) { return f << 4 & (HF2_SUBF | HF2_HCF); }
static inline unsigned cfFromF(unsigned f) { return f << 4 & 0x100; } static inline unsigned cfFromF(unsigned f) { return f << 4 & 0x100; }
void CPU::setStatePtrs(SaveState &state) { void CPU::setStatePtrs(SaveState &state) {
@ -89,7 +88,7 @@ void CPU::setStatePtrs(SaveState &state) {
void CPU::saveState(SaveState &state) { void CPU::saveState(SaveState &state) {
cycleCounter_ = memory.saveState(state, cycleCounter_); cycleCounter_ = memory.saveState(state, cycleCounter_);
calcHF(HF1, HF2); HF2 = updateHF2FromHF1(HF1, HF2);
state.cpu.cycleCounter = cycleCounter_; state.cpu.cycleCounter = cycleCounter_;
state.cpu.PC = PC_; state.cpu.PC = PC_;
@ -227,7 +226,7 @@ void CPU::loadState(const SaveState &state) {
// Test bitn in 8-bit value, check ZF, unset SF, set HCF: // Test bitn in 8-bit value, check ZF, unset SF, set HCF:
#define bitn_u8(bitmask, u8) do { \ #define bitn_u8(bitmask, u8) do { \
ZF = (u8) & (bitmask); \ ZF = (u8) & (bitmask); \
HF2 = 0x200; \ HF2 = HF2_HCF; \
} while (0) } while (0)
#define bit0_u8(u8) bitn_u8(0x01, (u8)) #define bit0_u8(u8) bitn_u8(0x01, (u8))
@ -337,7 +336,7 @@ void CPU::loadState(const SaveState &state) {
HF2 = u8; \ HF2 = u8; \
ZF = CF = A - HF2; \ ZF = CF = A - HF2; \
A = ZF & 0xFF; \ A = ZF & 0xFF; \
HF2 |= 0x400; \ HF2 |= HF2_SUBF; \
} while (0) } while (0)
// sbc a,r (4 cycles): // sbc a,r (4 cycles):
@ -345,7 +344,7 @@ void CPU::loadState(const SaveState &state) {
// Subtract CF and 8-bit value from A, check flags: // Subtract CF and 8-bit value from A, check flags:
#define sbc_a_u8(u8) do { \ #define sbc_a_u8(u8) do { \
HF1 = A; \ HF1 = A; \
HF2 = 0x400 | (CF & 0x100) | (u8); \ HF2 = HF2_SUBF | (CF & 0x100) | (u8); \
ZF = CF = A - ((CF >> 8) & 1) - (u8); \ ZF = CF = A - ((CF >> 8) & 1) - (u8); \
A = ZF & 0xFF; \ A = ZF & 0xFF; \
} while (0) } while (0)
@ -354,7 +353,7 @@ void CPU::loadState(const SaveState &state) {
// and a,(addr) (8 cycles): // and a,(addr) (8 cycles):
// bitwise and 8-bit value into A, check flags: // bitwise and 8-bit value into A, check flags:
#define and_a_u8(u8) do { \ #define and_a_u8(u8) do { \
HF2 = 0x200; \ HF2 = HF2_HCF; \
CF = 0; \ CF = 0; \
A &= (u8); \ A &= (u8); \
ZF = A; \ ZF = A; \
@ -385,13 +384,13 @@ void CPU::loadState(const SaveState &state) {
HF1 = A; \ HF1 = A; \
HF2 = u8; \ HF2 = u8; \
ZF = CF = A - HF2; \ ZF = CF = A - HF2; \
HF2 |= 0x400; \ HF2 |= HF2_SUBF; \
} while (0) } while (0)
// inc r (4 cycles): // inc r (4 cycles):
// Increment value of 8-bit register, check flags except CF: // Increment value of 8-bit register, check flags except CF:
#define inc_r(r) do { \ #define inc_r(r) do { \
HF2 = (r) | 0x800; \ HF2 = (r) | HF2_INCF; \
ZF = (r) + 1; \ ZF = (r) + 1; \
(r) = ZF & 0xFF; \ (r) = ZF & 0xFF; \
} while (0) } while (0)
@ -399,7 +398,7 @@ void CPU::loadState(const SaveState &state) {
// dec r (4 cycles): // dec r (4 cycles):
// Decrement value of 8-bit register, check flags except CF: // Decrement value of 8-bit register, check flags except CF:
#define dec_r(r) do { \ #define dec_r(r) do { \
HF2 = (r) | 0xC00; \ HF2 = (r) | HF2_INCF | HF2_SUBF; \
ZF = (r) - 1; \ ZF = (r) - 1; \
(r) = ZF & 0xFF; \ (r) = ZF & 0xFF; \
} while (0) } while (0)
@ -442,7 +441,7 @@ void CPU::loadState(const SaveState &state) {
\ \
const unsigned res = SP + disp; \ const unsigned res = SP + disp; \
CF = SP ^ disp ^ res; \ CF = SP ^ disp ^ res; \
HF2 = CF << 5 & 0x200; \ HF2 = CF << 5 & HF2_HCF; \
ZF = 1; \ ZF = 1; \
cycleCounter += 4; \ cycleCounter += 4; \
(sumout) = res & 0xFFFF; \ (sumout) = res & 0xFFFF; \
@ -715,15 +714,15 @@ void CPU::process(const unsigned long cycles) {
// daa (4 cycles): // daa (4 cycles):
// Adjust register A to correctly represent a BCD. Check ZF, HF and CF: // Adjust register A to correctly represent a BCD. Check ZF, HF and CF:
case 0x27: case 0x27:
calcHF(HF1, HF2); HF2 = updateHF2FromHF1(HF1, HF2);
{ {
unsigned correction = CF & 0x100 ? 0x60 : 0x00; unsigned correction = CF & 0x100 ? 0x60 : 0x00;
if (HF2 & 0x200) if (HF2 & HF2_HCF)
correction |= 0x06; correction |= 0x06;
if (!(HF2 &= 0x400)) { if (!(HF2 &= HF2_SUBF)) {
if ((A & 0x0F) > 0x09) if ((A & 0x0F) > 0x09)
correction |= 0x06; correction |= 0x06;
@ -786,7 +785,7 @@ void CPU::process(const unsigned long cycles) {
// cpl (4 cycles): // cpl (4 cycles):
// Complement register A. (Flip all bits), set SF and HCF: // Complement register A. (Flip all bits), set SF and HCF:
case 0x2F: case 0x2F:
HF2 = 0x600; HF2 = HF2_SUBF | HF2_HCF;
A ^= 0xFF; A ^= 0xFF;
break; break;
@ -841,7 +840,7 @@ void CPU::process(const unsigned long cycles) {
READ(HF2, addr); READ(HF2, addr);
ZF = HF2 + 1; ZF = HF2 + 1;
WRITE(addr, ZF & 0xFF); WRITE(addr, ZF & 0xFF);
HF2 |= 0x800; HF2 |= HF2_INCF;
} }
break; break;
@ -854,7 +853,7 @@ void CPU::process(const unsigned long cycles) {
READ(HF2, addr); READ(HF2, addr);
ZF = HF2 - 1; ZF = HF2 - 1;
WRITE(addr, ZF & 0xFF); WRITE(addr, ZF & 0xFF);
HF2 |= 0xC00; HF2 |= HF2_INCF | HF2_SUBF;
} }
break; break;
@ -1057,7 +1056,7 @@ void CPU::process(const unsigned long cycles) {
// A-A is always 0: // A-A is always 0:
case 0x97: case 0x97:
HF2 = 0x400; HF2 = HF2_SUBF;
CF = ZF = A = 0; CF = ZF = A = 0;
break; break;
@ -1082,7 +1081,7 @@ void CPU::process(const unsigned long cycles) {
case 0xA7: case 0xA7:
ZF = A; ZF = A;
CF = 0; CF = 0;
HF2 = 0x200; HF2 = HF2_HCF;
break; break;
case 0xA8: xor_a_u8(B); break; case 0xA8: xor_a_u8(B); break;
@ -1121,7 +1120,7 @@ void CPU::process(const unsigned long cycles) {
// A always equals A: // A always equals A:
case 0xBF: case 0xBF:
CF = ZF = 0; CF = ZF = 0;
HF2 = 0x400; HF2 = HF2_SUBF;
break; break;
// ret nz (20;8 cycles): // ret nz (20;8 cycles):
@ -1906,7 +1905,7 @@ void CPU::process(const unsigned long cycles) {
break; break;
case 0xF5: case 0xF5:
calcHF(HF1, HF2); HF2 = updateHF2FromHF1(HF1, HF2);
{ {
unsigned F = toF(HF2, CF, ZF); unsigned F = toF(HF2, CF, ZF);