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Convert set_logical_flags and set_arithmetic_flags to lambdas.

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This commit is contained in:
Thomas Harte 2024-01-16 10:13:30 -05:00
parent de038fe28f
commit 5b5ae69a18
1 changed files with 42 additions and 35 deletions
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77
Processors/Z80/Implementation/Z80Implementation.hpp
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@ -53,6 +53,39 @@ template < class T,
parity_overflow_result_ ^= parity_overflow_result_ >> 1;
};
/// Sets flags as expected at the end of a logical operation — an AND, OR or XOR.
/// Specifically:
/// * S, Z, 5 and 3 are set according to the value in A;
/// * P/V is set according to the parity of A;
/// * N and C are cleared; and
/// * H is set to whatever value is supplied as an argument.
const auto set_logical_flags = [&](uint8_t half_carry) {
sign_result_ = zero_result_ = bit53_result_ = a_;
set_parity(a_);
half_carry_result_ = half_carry;
subtract_flag_ = 0;
carry_result_ = 0;
set_did_compute_flags();
};
/// Sets flags as expected at the end of an arithmetic operation.
/// Specifically:
/// * S and Z are set according to result as trucated to 8 bits;
/// * C is set according to bit 8 of result;
/// * H is set according to whatever is supplied as half_result;
/// * V is set according to bit 7 of overflow;
/// * N is set to whatever is supplied as subtact; and
/// * 5 & 3 are set to the respective bits of bits53.
const auto set_arithmetic_flags = [&](int result, int half_result, int overflow, uint8_t subtract, uint8_t bits53) {
sign_result_ = zero_result_ = uint8_t(result);
carry_result_ = uint8_t(result >> 8);
half_carry_result_ = uint8_t(half_result);
parity_overflow_result_ = uint8_t(overflow >> 5);
subtract_flag_ = subtract;
bit53_result_ = bits53;
set_did_compute_flags();
};
number_of_cycles_ += cycles;
if(!scheduled_program_counter_) {
advance_operation();
@ -125,14 +158,6 @@ template < class T,
// MARK: - Logical
#define set_logical_flags(hf) \
sign_result_ = zero_result_ = bit53_result_ = a_; \
set_parity(a_); \
half_carry_result_ = hf; \
subtract_flag_ = 0; \
carry_result_ = 0; \
set_did_compute_flags();
case MicroOp::And:
a_ &= *static_cast<uint8_t *>(operation->source);
set_logical_flags(Flag::HalfCarry);
@ -148,8 +173,6 @@ template < class T,
set_logical_flags(0);
break;
#undef set_logical_flags
case MicroOp::CPL:
a_ ^= 0xff;
subtract_flag_ = Flag::Subtract;
@ -197,26 +220,17 @@ template < class T,
// MARK: - 8-bit arithmetic
#define set_arithmetic_flags(sub, b53) \
sign_result_ = zero_result_ = uint8_t(result); \
carry_result_ = uint8_t(result >> 8); \
half_carry_result_ = uint8_t(half_result); \
parity_overflow_result_ = uint8_t(overflow >> 5); \
subtract_flag_ = sub; \
bit53_result_ = uint8_t(b53); \
set_did_compute_flags();
case MicroOp::CP8: {
const uint8_t value = *static_cast<uint8_t *>(operation->source);
const int result = a_ - value;
const int half_result = (a_&0xf) - (value&0xf);
// overflow for a subtraction is when the signs were originally
// different and the result is different again
// Overflow for a subtraction is when the signs were originally
// different and the result is different again.
const int overflow = (value^a_) & (result^a_);
// the 5 and 3 flags come from the operand, atypically
set_arithmetic_flags(Flag::Subtract, value);
// The 5 and 3 flags come from the operand, atypically.
set_arithmetic_flags(result, half_result, overflow, Flag::Subtract, value);
} break;
case MicroOp::SUB8: {
@ -229,7 +243,7 @@ template < class T,
const int overflow = (value^a_) & (result^a_);
a_ = uint8_t(result);
set_arithmetic_flags(Flag::Subtract, result);
set_arithmetic_flags(result, half_result, overflow, Flag::Subtract, uint8_t(result));
} break;
case MicroOp::SBC8: {
@ -242,7 +256,7 @@ template < class T,
const int overflow = (value^a_) & (result^a_);
a_ = uint8_t(result);
set_arithmetic_flags(Flag::Subtract, result);
set_arithmetic_flags(result, half_result, overflow, Flag::Subtract, uint8_t(result));
} break;
case MicroOp::ADD8: {
@ -255,7 +269,7 @@ template < class T,
const int overflow = ~(value^a_) & (result^a_);
a_ = uint8_t(result);
set_arithmetic_flags(0, result);
set_arithmetic_flags(result, half_result, overflow, 0, uint8_t(result));
} break;
case MicroOp::ADC8: {
@ -268,23 +282,16 @@ template < class T,
const int overflow = ~(value^a_) & (result^a_);
a_ = uint8_t(result);
set_arithmetic_flags(0, result);
set_arithmetic_flags(result, half_result, overflow, 0, uint8_t(result));
} break;
#undef set_arithmetic_flags
case MicroOp::NEG: {
const int overflow = (a_ == 0x80);
const int result = -a_;
const int halfResult = -(a_&0xf);
a_ = uint8_t(result);
bit53_result_ = sign_result_ = zero_result_ = a_;
parity_overflow_result_ = overflow ? Flag::Overflow : 0;
subtract_flag_ = Flag::Subtract;
carry_result_ = uint8_t(result >> 8);
half_carry_result_ = uint8_t(halfResult);
set_did_compute_flags();
set_arithmetic_flags(result, halfResult, overflow ? 0xff : 0x00, Flag::Subtract, a_);
} break;
case MicroOp::Increment8: {