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Add INC instruction to the 6809 processor.

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Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>
This commit is contained in:
Adrian Conlon 2018-08-21 17:01:20 +01:00
parent 8c8c02f4b7
commit d44718ed22
2 changed files with 15 additions and 0 deletions
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1
MC6809/inc/mc6809.h
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@ -195,6 +195,7 @@ namespace EightBit {
uint8_t dec(uint8_t operand);
uint8_t eor(uint8_t operand, uint8_t data);
void exg(uint8_t data);
uint8_t inc(uint8_t operand);
uint8_t neg(uint8_t operand);
register16_t m_d;

14
MC6809/src/mc6809.cpp
View File

@ -187,6 +187,13 @@ int EightBit::mc6809::executeUnprefixed(uint8_t opcode) {
// EXG
case 0x1e: addCycles(8); exg(AM_immediate_byte()); break; // EXG (EXG R1,R2 immediate)
// INC
case 0x0c: addCycles(6); BUS().write(inc(AM_direct_byte())); break; // INC (INC direct)
case 0x4c: addCycles(2); A() = inc(A()); break; // INC (INCA inherent)
case 0x5c: addCycles(2); B() = inc(B()); break; // INC (INCB inherent)
case 0x6c: addCycles(6); BUS().write(inc(AM_indexed_byte())); break; // INC (INC indexed)
case 0x7c: addCycles(7); BUS().write(inc(AM_extended_byte())); break; // INC (INC extended)
default:
UNREACHABLE;
}
@ -572,3 +579,10 @@ void EightBit::mc6809::exg(uint8_t data) {
else
std::swap(referenceTransfer8(reg1), referenceTransfer8(reg2));
}
uint8_t EightBit::mc6809::inc(uint8_t operand) {
const uint8_t result = operand + 1;
adjustNZ(result);
adjustOverflow(operand, 1, result);
return result;
}