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Implements CMP and fixes a zero-flag error on 16-bit operations.

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This commit is contained in:
Thomas Harte 2020-10-06 21:47:26 -04:00
parent 5c809e5fbf
commit e068cbc103
2 changed files with 35 additions and 14 deletions
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5
Processors/6502Esque/Implementation/LazyFlags.hpp
View File

@ -37,6 +37,11 @@ struct LazyFlags {
zero_result = negative_result = value;
}
void set_nz(uint16_t value, int shift) {
negative_result = uint8_t(value >> shift);
zero_result = uint8_t(value | (value >> shift));
}
void set(uint8_t flags) {
carry = flags & Flag::Carry;
negative_result = flags & Flag::Sign;

44
Processors/65816/Implementation/65816Implementation.hpp
View File

@ -424,36 +424,36 @@ template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles
case INC:
++instruction_buffer_.value;
flags_.set_nz(m_top());
flags_.set_nz(instruction_buffer_.value, m_shift_);
break;;
case DEC:
--instruction_buffer_.value;
flags_.set_nz(m_top());
flags_.set_nz(instruction_buffer_.value, m_shift_);
break;
case INX: {
const uint16_t x_inc = x_.full + 1;
LD(x_, x_inc, x_masks_);
flags_.set_nz(x_top());
flags_.set_nz(x_.full, x_shift_);
} break;
case DEX: {
const uint16_t x_dec = x_.full - 1;
LD(x_, x_dec, x_masks_);
flags_.set_nz(x_top());
flags_.set_nz(x_.full, x_shift_);
} break;
case INY: {
const uint16_t y_inc = y_.full + 1;
LD(y_, y_inc, x_masks_);
flags_.set_nz(y_top());
flags_.set_nz(y_.full, x_shift_);
} break;
case DEY: {
const uint16_t y_dec = y_.full - 1;
LD(y_, y_dec, x_masks_);
flags_.set_nz(y_top());
flags_.set_nz(y_.full, x_shift_);
} break;
//
@ -462,17 +462,17 @@ template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles
case AND:
a_.full &= instruction_buffer_.value | m_masks_[0];
flags_.set_nz(a_top());
flags_.set_nz(a_.full, m_shift_);
break;
case EOR:
a_.full ^= instruction_buffer_.value;
flags_.set_nz(a_top());
flags_.set_nz(a_.full, m_shift_);
break;
case ORA:
a_.full |= instruction_buffer_.value;
flags_.set_nz(a_top());
flags_.set_nz(a_.full, m_shift_);
break;
//
@ -514,30 +514,46 @@ template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles
case ASL:
flags_.carry = data_buffer_.value >> (7 + m_shift_);
data_buffer_.value <<= 1;
flags_.set_nz(m_top());
flags_.set_nz(instruction_buffer_.value, m_shift_);
break;
case LSR:
flags_.carry = data_buffer_.value & 1;
data_buffer_.value >>= 1;
flags_.set_nz(m_top());
flags_.set_nz(instruction_buffer_.value, m_shift_);
break;
case ROL:
data_buffer_.value = (data_buffer_.value << 1) | flags_.carry;
flags_.carry = data_buffer_.value >> (7 + m_shift_);
flags_.set_nz(m_top());
flags_.set_nz(instruction_buffer_.value, m_shift_);
break;
case ROR: {
const uint8_t next_carry = data_buffer_.value & 1;
data_buffer_.value = (data_buffer_.value >> 1) | (flags_.carry << (7 + m_shift_));
flags_.carry = next_carry;
flags_.set_nz(m_top());
flags_.set_nz(instruction_buffer_.value, m_shift_);
} break;
//
// Arithmetic.
//
case CMP: {
if(m_flag()) {
const uint16_t temp16 = a_.halves.low - data_buffer_.value;
flags_.set_nz(uint8_t(temp16));
flags_.carry = ((~temp16) >> 8)&1;
} else {
const uint32_t temp32 = a_.full - data_buffer_.value;
flags_.set_nz(uint16_t(temp32), 8);
flags_.carry = ((~temp32) >> 16)&1;
}
} break;
// TODO:
// ADC, BIT, CMP, CPX, CPY, SBC,
// ADC, BIT, CPX, CPY, SBC,
// PLP,
// PHP, PHD, PHK,
// TRB, TSB,