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Add DEC and EOR instructions to the 6809

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Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>
This commit is contained in:
Adrian Conlon 2018-08-21 13:29:52 +01:00
parent 00ca20dbe4
commit f1f64dad93
2 changed files with 37 additions and 0 deletions
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2
MC6809/inc/mc6809.h
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@ -186,6 +186,8 @@ namespace EightBit {
uint8_t com(uint8_t operand);
void cwai(uint8_t data);
uint8_t da(uint8_t operand);
uint8_t dec(uint8_t operand);
uint8_t eor(uint8_t operand, uint8_t data);
uint8_t neg(uint8_t operand);
register16_t m_d;

35
MC6809/src/mc6809.cpp
View File

@ -161,6 +161,27 @@ int EightBit::mc6809::executeUnprefixed(uint8_t opcode) {
// DAA
case 0x19: addCycles(2); A() = da(A()); break; // DAA (DAA implied)
// DEC
case 0x0a: addCycles(6); BUS().write(dec(AM_direct_byte())); break; // DEC (DEC direct)
case 0x4a: addCycles(2); A() = dec(A()); break; // DEC (DECA inherent)
case 0x5a: addCycles(2); B() = dec(B()); break; // DEC (DECB inherent)
case 0x6a: addCycles(6); BUS().write(dec(AM_indexed_byte())); break; // DEC (DEC indexed)
case 0x7a: addCycles(7); BUS().write(dec(AM_extended_byte())); break; // DEC (DEC extended)
// EOR
// EORA
case 0x88: addCycles(2); A() = eor(A(), AM_immediate_byte()); break; // EOR (EORA immediate)
case 0x98: addCycles(4); A() = eor(A(), AM_direct_byte()); break; // EOR (EORA direct)
case 0xa8: addCycles(4); A() = eor(A(), AM_indexed_byte()); break; // EOR (EORA indexed)
case 0xb8: addCycles(5); A() = eor(A(), AM_extended_byte()); break; // EOR (EORA extended)
// EORB
case 0xc8: addCycles(2); B() = eor(B(), AM_immediate_byte()); break; // EOR (EORB immediate)
case 0xd8: addCycles(4); B() = eor(B(), AM_direct_byte()); break; // EOR (EORB direct)
case 0xe8: addCycles(4); B() = eor(B(), AM_indexed_byte()); break; // EOR (EORB indexed)
case 0xf8: addCycles(5); B() = eor(B(), AM_extended_byte()); break; // EOR (EORB extended)
default:
UNREACHABLE;
}
@ -484,3 +505,17 @@ uint8_t EightBit::mc6809::da(uint8_t operand) {
adjustNZ(A());
}
uint8_t EightBit::mc6809::dec(uint8_t operand) {
const uint8_t result = operand - 1;
adjustNZ(result);
adjustOverflow(operand, 1, result);
return result;
}
uint8_t EightBit::mc6809::eor(uint8_t operand, uint8_t data) {
const uint8_t result = operand ^ data;
adjustNZ(result);
clearFlag(CC(), VF);
return result;
}