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Tidy the Z80 BIT implementation for better code resuse. No functional change 

Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>
This commit is contained in:
Adrian Conlon 2018-12-01 13:01:33 +00:00
parent 802ad6041d
commit cf0828c595
2 changed files with 33 additions and 58 deletions
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2
Z80/inc/Z80.h
View File

@ -359,7 +359,7 @@ namespace EightBit {
[[nodiscard]] uint8_t sll(uint8_t operand);
[[nodiscard]] uint8_t srl(uint8_t operand);
uint8_t bit(int n, uint8_t operand);
void bit(int n, uint8_t operand);
[[nodiscard]] static uint8_t res(int n, uint8_t operand);
[[nodiscard]] static uint8_t set(int n, uint8_t operand);

89
Z80/src/Z80.cpp
View File

@ -404,15 +404,14 @@ uint8_t EightBit::Z80::srl(const uint8_t operand) {
return result;
}
uint8_t EightBit::Z80::bit(const int n, const uint8_t operand) {
void EightBit::Z80::bit(const int n, const uint8_t operand) {
ASSUME(n >= 0);
ASSUME(n <= 7);
setFlag(F(), HC);
clearFlag(F(), NF);
const auto discarded = operand & (1 << n);
adjustSZXY<Z80>(F(), discarded);
adjustSZ<Z80>(F(), discarded);
clearFlag(F(), PF, discarded);
return operand;
}
uint8_t EightBit::Z80::res(const int n, const uint8_t operand) {
@ -724,9 +723,12 @@ void EightBit::Z80::executeCB(const int x, const int y, const int z) {
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) : BUS().read(displacedAddress());
const bool update = x != 1; // BIT does not update
switch (x) {
case 0: { // rot[y] r[z]
auto operand = LIKELY(!m_displaced) ? R(z) : BUS().read(displacedAddress());
switch (y) {
case 0:
operand = rlc(operand);
@ -756,64 +758,39 @@ void EightBit::Z80::executeCB(const int x, const int y, const int z) {
UNREACHABLE;
}
adjustSZP<Z80>(F(), operand);
addCycles(8);
break;
} case 1: // BIT y, r[z]
addCycles(8);
bit(y, operand);
if (LIKELY(direct)) {
adjustXY<Z80>(F(), operand);
} else {
adjustXY<Z80>(F(), MEMPTR().high);
addCycles(4);
}
break;
case 2: // RES y, r[z]
addCycles(8);
operand = res(y, operand);
break;
case 3: // SET y, r[z]
addCycles(8);
operand = set(y, operand);
break;
default:
UNREACHABLE;
}
if (LIKELY(update)) {
if (LIKELY(!m_displaced)) {
R(z, operand);
if (UNLIKELY(memoryZ))
addCycles(7);
} else {
if (LIKELY(z != 6))
R2(z, operand);
BUS().write(operand);
addCycles(15);
}
addCycles(8);
break;
} case 1: // BIT y, r[z]
addCycles(8);
if (LIKELY(!m_displaced)) {
const auto operand = bit(y, R(z));
if (LIKELY(z != 6)) {
adjustXY<Z80>(F(), operand);
} else {
adjustXY<Z80>(F(), MEMPTR().high);
addCycles(4);
}
} else {
bit(y, BUS().read(displacedAddress()));
adjustXY<Z80>(F(), MEMPTR().high);
addCycles(12);
}
break;
case 2: // RES y, r[z]
addCycles(8);
if (LIKELY(!m_displaced)) {
R(z, res(y, R(z)));
if (UNLIKELY(memoryZ))
addCycles(7);
} else {
auto operand = BUS().read(displacedAddress());
operand = res(y, operand);
BUS().write(operand);
R2(z, operand);
addCycles(15);
}
break;
case 3: // SET y, r[z]
addCycles(8);
if (LIKELY(!m_displaced)) {
R(z, set(y, R(z)));
if (UNLIKELY(memoryZ))
addCycles(7);
} else {
auto operand = BUS().read(displacedAddress());
operand = set(y, operand);
BUS().write(operand);
R2(z, operand);
addCycles(15);
}
break;
default:
UNREACHABLE;
}
}
@ -900,7 +877,9 @@ void EightBit::Z80::executeED(const int x, const int y, const int z, const int p
case 6: // Set interrupt mode
switch (y) {
case 0:
case 1:
case 4:
case 5:
IM() = 0;
break;
case 2:
@ -911,10 +890,6 @@ void EightBit::Z80::executeED(const int x, const int y, const int z, const int p
case 7:
IM() = 2;
break;
case 1:
case 5:
IM() = 0;
break;
default:
UNREACHABLE;
}