From 4be4a0603edc69c9249407d95d24a890e36ee91c Mon Sep 17 00:00:00 2001 From: Adrian Conlon Date: Sat, 14 Sep 2019 15:04:46 +0100 Subject: [PATCH] Refactor the Z80 implementation to: a) Simplify M1 handling b) Reuse subtract/add implementations c) Simplify conditional code blocks. Signed-off-by: Adrian Conlon --- Z80/inc/Z80.h | 14 +-- Z80/src/Z80.cpp | 277 +++++++++++++++++++++--------------------------- 2 files changed, 128 insertions(+), 163 deletions(-) diff --git a/Z80/inc/Z80.h b/Z80/inc/Z80.h index 599404f..bebbc46 100644 --- a/Z80/inc/Z80.h +++ b/Z80/inc/Z80.h @@ -310,14 +310,14 @@ namespace EightBit { bool jumpConditionalFlag(int flag); bool callConditionalFlag(int flag); - void sbc(register16_t value); - void adc(register16_t value); - void add(register16_t value); + register16_t sbc(register16_t operand, register16_t value); + register16_t adc(register16_t operand, register16_t value); + register16_t add(register16_t operand, register16_t value, int carry = 0); - void add(uint8_t value, int carry = 0); - void adc(uint8_t value); - void sub(uint8_t value, int carry = 0); - void sbc(uint8_t value); + [[nodiscard]] uint8_t add(uint8_t operand, uint8_t value, int carry = 0); + [[nodiscard]] uint8_t adc(uint8_t operand, uint8_t value); + [[nodiscard]] uint8_t sub(uint8_t operand, uint8_t value, int carry = 0); + [[nodiscard]] uint8_t sbc(uint8_t operand, uint8_t value); void andr(uint8_t value); void xorr(uint8_t value); void orr(uint8_t value); diff --git a/Z80/src/Z80.cpp b/Z80/src/Z80.cpp index 6a6ab3e..f2c0b35 100644 --- a/Z80/src/Z80.cpp +++ b/Z80/src/Z80.cpp @@ -22,6 +22,10 @@ EightBit::Z80::Z80(Bus& bus, InputOutput& ports) m_prefixCB = m_prefixDD = m_prefixED = m_prefixFD = false; }); + + LoweredM1.connect([this](EventArgs) { + ++REFRESH(); + }); } DEFINE_PIN_LEVEL_CHANGERS(NMI, Z80); @@ -204,82 +208,77 @@ bool EightBit::Z80::callConditionalFlag(const int flag) { } } -void EightBit::Z80::sbc(const register16_t value) { +EightBit::register16_t EightBit::Z80::sbc(const register16_t operand, const register16_t value) { - MEMPTR() = HL2(); + const auto subtraction = operand.word - value.word - (F() & CF); - const auto beforeNegative = MEMPTR().high & SF; - const auto valueNegative = value.high & SF; + const register16_t result = subtraction; - const auto result = MEMPTR().word - value.word - (F() & CF); - HL2() = result; - - const auto afterNegative = HL2().high & SF; - - setFlag(F(), SF, afterNegative); - clearFlag(F(), ZF, HL2().word); - adjustHalfCarrySub(F(), MEMPTR().high, value.high, HL2().high); - adjustOverflowSub(F(), beforeNegative, valueNegative, afterNegative); setFlag(F(), NF); - setFlag(F(), CF, result & Bit16); - adjustXY(F(), HL2().high); + clearFlag(F(), ZF, result.word); + setFlag(F(), CF, subtraction & Bit16); + adjustHalfCarrySub(F(), operand.high, value.high, result.high); + adjustXY(F(), result.high); - ++MEMPTR(); -} - -void EightBit::Z80::adc(const register16_t value) { - - MEMPTR() = HL2(); - - const auto beforeNegative = MEMPTR().high & SF; + const auto beforeNegative = operand.high & SF; const auto valueNegative = value.high & SF; - - const auto result = MEMPTR().word + value.word + (F() & CF); - HL2() = result; - - const auto afterNegative = HL2().high & SF; + const auto afterNegative = result.high & SF; + + setFlag(F(), SF, afterNegative); + adjustOverflowSub(F(), beforeNegative, valueNegative, afterNegative); + + MEMPTR() = operand + 1; + + return result; +} + +EightBit::register16_t EightBit::Z80::adc(const register16_t operand, const register16_t value) { + + const auto result = add(operand, value, F() & CF); + clearFlag(F(), ZF, result.word); + + const auto beforeNegative = operand.high & SF; + const auto valueNegative = value.high & SF; + const auto afterNegative = result.high & SF; setFlag(F(), SF, afterNegative); - clearFlag(F(), ZF, HL2().word); - adjustHalfCarryAdd(F(), MEMPTR().high, value.high, HL2().high); adjustOverflowAdd(F(), beforeNegative, valueNegative, afterNegative); - clearFlag(F(), NF); - setFlag(F(), CF, result & Bit16); - adjustXY(F(), HL2().high); - ++MEMPTR(); + return result; } -void EightBit::Z80::add(const register16_t value) { +EightBit::register16_t EightBit::Z80::add(const register16_t operand, const register16_t value, int carry) { - MEMPTR() = HL2(); - - const auto result = MEMPTR().word + value.word; - - HL2() = result; + const int addition = operand.word + value.word + carry; + const register16_t result = addition; clearFlag(F(), NF); - setFlag(F(), CF, result & Bit16); - adjustHalfCarryAdd(F(), MEMPTR().high, value.high, HL2().high); - adjustXY(F(), HL2().high); + setFlag(F(), CF, addition & Bit16); + adjustHalfCarryAdd(F(), operand.high, value.high, result.high); + adjustXY(F(), result.high); - ++MEMPTR(); + MEMPTR() = operand + 1; + + return result; } -void EightBit::Z80::add(const uint8_t value, const int carry) { +uint8_t EightBit::Z80::add(const uint8_t operand, const uint8_t value, const int carry) { - const register16_t result = A() + value + carry; + const register16_t addition = operand + value + carry; + const auto result = addition.low; - adjustHalfCarryAdd(F(), A(), value, result.low); - adjustOverflowAdd(F(), A(), value, result.low); + adjustHalfCarryAdd(F(), operand, value, result); + adjustOverflowAdd(F(), operand, value, result); clearFlag(F(), NF); - setFlag(F(), CF, result.high & CF); - adjustSZXY(F(), A() = result.low); + setFlag(F(), CF, addition.high & CF); + adjustSZXY(F(), result); + + return result; } -void EightBit::Z80::adc(const uint8_t value) { - add(value, F() & CF); +uint8_t EightBit::Z80::adc(const uint8_t operand, const uint8_t value) { + return add(operand, value, F() & CF); } uint8_t EightBit::Z80::subtract(const uint8_t operand, const uint8_t value, const int carry) { @@ -297,13 +296,14 @@ uint8_t EightBit::Z80::subtract(const uint8_t operand, const uint8_t value, cons return result; } -void EightBit::Z80::sub(const uint8_t value, const int carry) { - A() = subtract(A(), value, carry); - adjustXY(F(), A()); +uint8_t EightBit::Z80::sub(const uint8_t operand, const uint8_t value, const int carry) { + const auto subtraction = subtract(operand, value, carry); + adjustXY(F(), subtraction); + return subtraction; } -void EightBit::Z80::sbc(const uint8_t value) { - sub(value, F() & CF); +uint8_t EightBit::Z80::sbc(const uint8_t operand, const uint8_t value) { + return sub(operand, value, F() & CF); } void EightBit::Z80::andr(const uint8_t value) { @@ -658,7 +658,6 @@ int EightBit::Z80::step() { ExecutingInstruction.fire(*this); if (LIKELY(powered())) { m_displaced = m_prefixCB = m_prefixDD = m_prefixED = m_prefixFD = false; - lowerM1(); bool handled = false; if (lowered(RESET())) { handleRESET(); @@ -676,8 +675,10 @@ int EightBit::Z80::step() { execute(0); // NOP handled = true; } - if (!handled) + if (!handled) { + lowerM1(); execute(fetchByte()); + } } ExecutedInstruction.fire(*this); return cycles(); @@ -685,12 +686,7 @@ int EightBit::Z80::step() { int EightBit::Z80::execute() { - ASSUME(lowered(M1())); - - if (LIKELY(!(m_prefixCB && m_displaced))) { - ++REFRESH(); - raiseM1(); - } + raiseM1(); const auto& decoded = getDecodedOpcode(opcode()); @@ -701,34 +697,22 @@ int EightBit::Z80::execute() { const auto p = decoded.p; const auto q = decoded.q; - const auto prefixed = m_prefixCB || m_prefixED; - if (LIKELY(!prefixed)) { + if (m_prefixCB) + executeCB(x, y, z); + else if (m_prefixED) + executeED(x, y, z, p, q); + else executeOther(x, y, z, p, q); - } else { - if (m_prefixCB) - executeCB(x, y, z); - else if (m_prefixED) - executeED(x, y, z, p, q); - else - UNREACHABLE; - } ASSUME(cycles() > 0); return cycles(); } void EightBit::Z80::executeCB(const int x, const int y, const int z) { - ASSUME(x >= 0); - ASSUME(x <= 3); - ASSUME(y >= 0); - ASSUME(y <= 7); - ASSUME(z >= 0); - ASSUME(z <= 7); const bool memoryY = y == 6; const bool memoryZ = z == 6; const bool indirect = (!m_displaced && memoryZ) || m_displaced; - const bool direct = !indirect; - auto operand = LIKELY(!m_displaced) ? R(z) : busRead(displacedAddress()); + auto operand = m_displaced ? busRead(displacedAddress()) : R(z); const bool update = x != 1; // BIT does not update switch (x) { case 0: { // rot[y] r[z] @@ -766,11 +750,11 @@ void EightBit::Z80::executeCB(const int x, const int y, const int z) { } case 1: // BIT y, r[z] tick(8); bit(y, operand); - if (LIKELY(direct)) { - adjustXY(F(), operand); - } else { + if (indirect) { adjustXY(F(), MEMPTR().high); tick(4); + } else { + adjustXY(F(), operand); } break; case 2: // RES y, r[z] @@ -784,31 +768,21 @@ void EightBit::Z80::executeCB(const int x, const int y, const int z) { default: UNREACHABLE; } - if (LIKELY(update)) { - if (LIKELY(!m_displaced)) { - R(z, operand); - if (UNLIKELY(memoryZ)) - tick(7); - } else { + if (update) { + if (m_displaced) { busWrite(operand); - if (LIKELY(!memoryZ)) + if (!memoryZ) R2(z, operand); tick(15); + } else { + R(z, operand); + if (memoryZ) + tick(7); } } } void EightBit::Z80::executeED(const int x, const int y, const int z, const int p, const int q) { - ASSUME(x >= 0); - ASSUME(x <= 3); - ASSUME(y >= 0); - ASSUME(y <= 7); - ASSUME(z >= 0); - ASSUME(z <= 7); - ASSUME(p >= 0); - ASSUME(p <= 3); - ASSUME(q >= 0); - ASSUME(q <= 1); const bool memoryY = y == 6; const bool memoryZ = z == 6; switch (x) { @@ -821,7 +795,7 @@ void EightBit::Z80::executeED(const int x, const int y, const int z, const int p case 0: // Input from port with 16-bit address (MEMPTR() = BUS().ADDRESS() = BC())++; readPort(); - if (LIKELY(y != 6)) // IN r[y],(C) + if (y != 6) // IN r[y],(C) R(y, BUS().DATA()); adjustSZPXY(F(), BUS().DATA()); clearFlag(F(), NF | HC); @@ -829,20 +803,20 @@ void EightBit::Z80::executeED(const int x, const int y, const int z, const int p break; case 1: // Output to port with 16-bit address (MEMPTR() = BUS().ADDRESS() = BC())++; - if (LIKELY(y != 6)) // OUT (C),r[y] - BUS().DATA() = R(y); - else // OUT (C),0 + if (y == 6) // OUT (C),0 BUS().DATA() = 0; + else // OUT (C),r[y] + BUS().DATA() = R(y); writePort(); tick(12); break; case 2: // 16-bit add/subtract with carry switch (q) { case 0: // SBC HL, rp[p] - sbc(RP(p)); + HL2() = sbc(HL2(), RP(p)); break; case 1: // ADC HL, rp[p] - adc(RP(p)); + HL2() = adc(HL2(), RP(p)); break; default: UNREACHABLE; @@ -952,14 +926,14 @@ void EightBit::Z80::executeED(const int x, const int y, const int z, const int p ldd(); break; case 6: // LDIR - if (LIKELY(ldir())) { + if (ldir()) { MEMPTR() = --PC(); --PC(); tick(5); } break; case 7: // LDDR - if (LIKELY(lddr())) { + if (lddr()) { MEMPTR() = --PC(); --PC(); tick(5); @@ -976,14 +950,14 @@ void EightBit::Z80::executeED(const int x, const int y, const int z, const int p cpd(); break; case 6: // CPIR - if (LIKELY(cpir())) { + if (cpir()) { MEMPTR() = --PC(); --PC(); tick(5); } break; case 7: // CPDR - if (LIKELY(cpdr())) { + if (cpdr()) { MEMPTR() = --PC(); --PC(); tick(5); @@ -1002,13 +976,13 @@ void EightBit::Z80::executeED(const int x, const int y, const int z, const int p ind(); break; case 6: // INIR - if (LIKELY(inir())) { + if (inir()) { PC() -= 2; tick(5); } break; case 7: // INDR - if (LIKELY(indr())) { + if (indr()) { PC() -= 2; tick(5); } @@ -1024,13 +998,13 @@ void EightBit::Z80::executeED(const int x, const int y, const int z, const int p outd(); break; case 6: // OTIR - if (LIKELY(otir())) { + if (otir()) { PC() -= 2; tick(5); } break; case 7: // OTDR - if (LIKELY(otdr())) { + if (otdr()) { PC() -= 2; tick(5); } @@ -1044,16 +1018,6 @@ void EightBit::Z80::executeED(const int x, const int y, const int z, const int p } void EightBit::Z80::executeOther(const int x, const int y, const int z, const int p, const int q) { - ASSUME(x >= 0); - ASSUME(x <= 3); - ASSUME(y >= 0); - ASSUME(y <= 7); - ASSUME(z >= 0); - ASSUME(z <= 7); - ASSUME(p >= 0); - ASSUME(p <= 3); - ASSUME(q >= 0); - ASSUME(q <= 1); const bool memoryY = y == 6; const bool memoryZ = z == 6; switch (x) { @@ -1069,7 +1033,7 @@ void EightBit::Z80::executeOther(const int x, const int y, const int z, const in tick(4); break; case 2: // DJNZ d - if (LIKELY(jrConditional(--B()))) + if (jrConditional(--B())) tick(5); tick(8); break; @@ -1081,7 +1045,7 @@ void EightBit::Z80::executeOther(const int x, const int y, const int z, const in case 5: case 6: case 7: - if (UNLIKELY(jrConditionalFlag(y - 4))) + if (jrConditionalFlag(y - 4)) tick(5); tick(5); break; @@ -1096,7 +1060,7 @@ void EightBit::Z80::executeOther(const int x, const int y, const int z, const in tick(10); break; case 1: // ADD HL,rp - add(RP(p)); + HL2() = add(HL2(), RP(p)); tick(11); break; default: @@ -1178,24 +1142,24 @@ void EightBit::Z80::executeOther(const int x, const int y, const int z, const in tick(6); break; case 4: // 8-bit INC - if (UNLIKELY(m_displaced && memoryY)) + if (m_displaced && memoryY) fetchDisplacement(); R(y, increment(R(y))); tick(4); break; case 5: // 8-bit DEC - if (UNLIKELY(memoryY)) { + if (memoryY) { tick(7); - if (UNLIKELY(m_displaced)) + if (m_displaced) fetchDisplacement(); } R(y, decrement(R(y))); tick(4); break; case 6: // 8-bit load immediate - if (UNLIKELY(memoryY)) { + if (memoryY) { tick(3); - if (UNLIKELY(m_displaced)) + if (m_displaced) fetchDisplacement(); } R(y, fetchByte()); // LD r,n @@ -1237,10 +1201,12 @@ void EightBit::Z80::executeOther(const int x, const int y, const int z, const in } break; case 1: // 8-bit loading - if (LIKELY(!(memoryZ && memoryY))) { + if ((memoryZ && memoryY)) { // Exception (replaces LD (HL), (HL)) + lowerHALT(); + } else { bool normal = true; - if (UNLIKELY(m_displaced)) { - if (LIKELY(memoryZ || memoryY)) + if (m_displaced) { + if (memoryZ || memoryY) fetchDisplacement(); if (memoryZ) { switch (y) { @@ -1267,34 +1233,32 @@ void EightBit::Z80::executeOther(const int x, const int y, const int z, const in } } } - if (LIKELY(normal)) + if (normal) R(y, R(z)); - if (UNLIKELY(memoryY || memoryZ)) // M operations + if (memoryY || memoryZ) // M operations tick(3); - } else { // Exception (replaces LD (HL), (HL)) - lowerHALT(); } tick(4); break; case 2: { // Operate on accumulator and register/memory location - if (UNLIKELY(memoryZ)) { + if (memoryZ) { tick(3); - if (UNLIKELY(m_displaced)) + if (m_displaced) fetchDisplacement(); } const auto value = R(z); switch (y) { case 0: // ADD A,r - add(value); + A() = add(A(), value); break; case 1: // ADC A,r - adc(value); + A() = adc(A(), value); break; case 2: // SUB r - sub(value); + A() = sub(A(), value); break; case 3: // SBC A,r - sbc(value); + A() = sbc(A(), value); break; case 4: // AND r andr(value); @@ -1317,7 +1281,7 @@ void EightBit::Z80::executeOther(const int x, const int y, const int z, const in case 3: switch (z) { case 0: // Conditional return - if (UNLIKELY(returnConditionalFlag(y))) + if (returnConditionalFlag(y)) tick(6); tick(5); break; @@ -1365,9 +1329,10 @@ void EightBit::Z80::executeOther(const int x, const int y, const int z, const in break; case 1: // CB prefix m_prefixCB = true; - if (UNLIKELY(m_displaced)) + if (m_displaced) fetchDisplacement(); - lowerM1(); + else + lowerM1(); execute(fetchByte()); break; case 2: // OUT (n),A @@ -1399,7 +1364,7 @@ void EightBit::Z80::executeOther(const int x, const int y, const int z, const in } break; case 4: // Conditional call: CALL cc[y], nn - if (UNLIKELY(callConditionalFlag(y))) + if (callConditionalFlag(y)) tick(7); tick(10); break; @@ -1442,16 +1407,16 @@ void EightBit::Z80::executeOther(const int x, const int y, const int z, const in const auto operand = fetchByte(); switch (y) { case 0: // ADD A,n - add(operand); + A() = add(A(), operand); break; case 1: // ADC A,n - adc(operand); + A() = adc(A(), operand); break; case 2: // SUB n - sub(operand); + A() = sub(A(), operand); break; case 3: // SBC A,n - sbc(operand); + A() = sbc(A(), operand); break; case 4: // AND n andr(operand);