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Implementing DEX & DEY

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This commit is contained in:
Anonymus Raccoon
2020-04-03 15:14:19 +02:00
parent 7407c3cfaa
commit 9f8ae6cb08
4 changed files with 39 additions and 11 deletions
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sources/CPU/CPU.hpp
+6 -2
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@@ -374,6 +374,10 @@ namespace ComSquare::CPU
int JML(uint24_t valueAddr, AddressingMode);
//! @brief No OP.
int NOP(uint24_t, AddressingMode);
//! @brief Decrement the X register.
int DEX(uint24_t, AddressingMode);
//! @brief Decrement the Y register.
int DEY(uint24_t, AddressingMode);
//! @brief All the instructions of the CPU.
//! @info Instructions are indexed by their opcode
@@ -514,7 +518,7 @@ namespace ComSquare::CPU
{&CPU::STA, 3, "sta", AddressingMode::DirectPage, 2}, // 85
{&CPU::STX, 3, "stx", AddressingMode::DirectPage, 2}, // 86
{&CPU::STA, 6, "sta", AddressingMode::DirectPageIndirectLong, 2}, // 87
{&CPU::BRK, 7, "dey #-#", AddressingMode::Implied, 2}, // 88
{&CPU::DEY, 2, "dey", AddressingMode::Implied, 1}, // 88
{&CPU::BRK, 7, "bit #-#", AddressingMode::Implied, 2}, // 89
{&CPU::BRK, 7, "txa #-#", AddressingMode::Implied, 2}, // 8A
{&CPU::PHB, 3, "phb", AddressingMode::Implied, 1}, // 8B
@@ -580,7 +584,7 @@ namespace ComSquare::CPU
{&CPU::BRK, 7, "cmp #-#", AddressingMode::Implied, 2}, // C7
{&CPU::INY, 2, "iny", AddressingMode::Implied, 1}, // C8
{&CPU::BRK, 7, "cmp #-#", AddressingMode::Implied, 2}, // C9
{&CPU::BRK, 7, "dex #-#", AddressingMode::Implied, 2}, // CA
{&CPU::DEX, 2, "dex", AddressingMode::Implied, 1}, // CA
{&CPU::BRK, 7, "wai #-#", AddressingMode::Implied, 2}, // CB
{&CPU::BRK, 7, "cpy #-#", AddressingMode::Implied, 2}, // CC
{&CPU::BRK, 7, "cmp #-#", AddressingMode::Implied, 2}, // CD
sources/CPU/Instructions/MathematicalOperations.cpp
+29 -5
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@@ -12,8 +12,8 @@ namespace ComSquare::CPU
unsigned value = this->_bus->read(valueAddr) + this->_registers.p.c;
if (!this->_registers.p.m)
value += this->_bus->read(valueAddr + 1) << 8u;
unsigned negativeMask = this->_isEmulationMode ? 0x80u : 0x8000u;
unsigned maxValue = this->_isEmulationMode ? UINT8_MAX : UINT16_MAX;
unsigned negativeMask = this->_registers.p.m ? 0x80u : 0x8000u;
unsigned maxValue = this->_registers.p.m ? UINT8_MAX : UINT16_MAX;
this->_registers.p.c = static_cast<unsigned>(this->_registers.a) + value > maxValue;
if ((this->_registers.a & negativeMask) == (value & negativeMask))
@@ -21,7 +21,7 @@ namespace ComSquare::CPU
else
this->_registers.p.v = false;
this->_registers.a += value;
if (this->_isEmulationMode)
if (this->_registers.p.m)
this->_registers.a %= 0x100;
this->_registers.p.z = this->_registers.a == 0;
this->_registers.p.n = this->_registers.a & negativeMask;
@@ -51,7 +51,7 @@ namespace ComSquare::CPU
int CPU::SBC(uint24_t valueAddr, AddressingMode mode)
{
unsigned negativeMask = this->_isEmulationMode ? 0x80u : 0x8000u;
unsigned negativeMask = this->_registers.p.m ? 0x80u : 0x8000u;
unsigned value = this->_bus->read(valueAddr);
if (!this->_registers.p.m)
value += this->_bus->read(valueAddr + 1) << 8u;
@@ -63,7 +63,7 @@ namespace ComSquare::CPU
else
this->_registers.p.v = false;
this->_registers.a += ~value + oldCarry;
if (this->_isEmulationMode)
if (this->_registers.p.m)
this->_registers.a %= 0x100;
this->_registers.p.z = this->_registers.a == 0;
this->_registers.p.n = this->_registers.a & negativeMask;
@@ -90,4 +90,28 @@ namespace ComSquare::CPU
}
return cycles;
}
int CPU::DEX(uint24_t, AddressingMode)
{
unsigned negativeMask = this->_registers.p.x_b ? UINT8_MAX : UINT16_MAX;
this->_registers.x--;
if (this->_registers.p.x_b)
this->_registers.xh = 0;
this->_registers.p.z = this->_registers.x == 0;
this->_registers.p.n = this->_registers.x & negativeMask;
return 0;
}
int CPU::DEY(uint24_t, AddressingMode)
{
unsigned negativeMask = this->_registers.p.x_b ? UINT8_MAX : UINT16_MAX;
this->_registers.y--;
if (this->_registers.p.x_b)
this->_registers.yh = 0;
this->_registers.p.z = this->_registers.y == 0;
this->_registers.p.n = this->_registers.y & negativeMask;
return 0;
}
}
tests/CPU/Math/testADC.cpp
+3 -3
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@@ -67,7 +67,7 @@ Test(ADC, overflowEmulation)
Test(ADC, signedOverflow)
{
Init()
snes.cpu->_isEmulationMode = false;
snes.cpu->_registers.p.m = false;
snes.cpu->_registers.a = 0x7FFF;
snes.wram->_data[0] = 0x1;
snes.cpu->ADC(0x0, ComSquare::CPU::AddressingMode::Implied);
@@ -81,7 +81,7 @@ Test(ADC, signedOverflow)
Test(ADC, signedOverflowEmulated)
{
Init()
snes.cpu->_isEmulationMode = true;
snes.cpu->_registers.p.m = true;
snes.cpu->_registers.a = 0x007F;
snes.wram->_data[0] = 0x1;
snes.cpu->ADC(0x0, ComSquare::CPU::AddressingMode::Implied);
@@ -95,7 +95,7 @@ Test(ADC, signedOverflowEmulated)
Test(ADC, negative)
{
Init()
snes.cpu->_isEmulationMode = false;
snes.cpu->_registers.p.m = false;
snes.cpu->_registers.a = 0x8FFF;
snes.wram->_data[0] = 0x1;
snes.cpu->ADC(0x0, ComSquare::CPU::AddressingMode::Implied);
tests/CPU/Math/testSBC.cpp
+1 -1
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@@ -62,7 +62,7 @@ Test(SBC, overflowEmulation)
Init()
snes.cpu->_isEmulationMode = true;
snes.cpu->_registers.a = 0x1;
snes.cpu->_registers.p.m = false;
snes.cpu->_registers.p.m = true;
snes.cpu->_registers.p.c = false;
snes.wram->_data[0] = 0x02;
snes.cpu->SBC(0x0, ComSquare::CPU::AddressingMode::Implied);