6502/CLK
1
0
Fork 0
mirror of https://github.com/TomHarte/CLK.git synced 2024-11-26 23:52:26 +00:00
Code Issues Projects Releases Wiki Activity

Generalise CBW.

Browse Source
This commit is contained in:
Thomas Harte 2023-10-09 15:00:04 -04:00
parent 08aed3bac5
commit fe6e2eb0a1
1 changed files with 18 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
InstructionSets/x86/Implementation/PerformImplementation.hpp
View File

@ -493,12 +493,20 @@ void call_far(InstructionT &instruction,
flow_controller.call(segment, offset); flow_controller.call(segment, offset);
} }
inline void cbw(CPU::RegisterPair16 &ax) { template <typename IntT>
ax.halves.high = (ax.halves.low & 0x80) ? 0xff : 0x00; void cbw(IntT &ax) {
constexpr IntT test_bit = 1 << (sizeof(IntT) * 4 - 1);
constexpr IntT low_half = (1 << (sizeof(IntT) * 4)) - 1;
if(ax & test_bit) {
ax |= ~low_half;
} else {
ax &= low_half;
}
} }
template <typename IntT> template <typename IntT>
inline void cwd(IntT &dx, IntT ax) { void cwd(IntT &dx, IntT ax) {
dx = ax & top_bit<IntT>() ? IntT(~0) : IntT(0); dx = ax & top_bit<IntT>() ? IntT(~0) : IntT(0);
} }
@ -567,7 +575,13 @@ template <
case Operation::DAA: Primitive::daa(registers.al(), status); return; case Operation::DAA: Primitive::daa(registers.al(), status); return;
case Operation::DAS: Primitive::das(registers.al(), status); return; case Operation::DAS: Primitive::das(registers.al(), status); return;
case Operation::CBW: Primitive::cbw(registers.axp()); return; case Operation::CBW:
if constexpr (data_size == DataSize::Word) {
Primitive::cbw(registers.ax());
} else if constexpr (is_32bit(model) && data_size == DataSize::DWord) {
Primitive::cbw(registers.eax());
}
return;
case Operation::CWD: case Operation::CWD:
if constexpr (data_size == DataSize::Word) { if constexpr (data_size == DataSize::Word) {
Primitive::cwd(registers.dx(), registers.ax()); Primitive::cwd(registers.dx(), registers.ax());