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Takes a run at most of the remaining addressing modes.

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This commit is contained in:
Thomas Harte 2021-01-17 21:52:16 -05:00
parent dea79c6dea
commit 4982430a29
1 changed files with 38 additions and 11 deletions
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49
InstructionSets/M50740/Executor.cpp
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@ -32,6 +32,8 @@ template <Operation operation, AddressingMode addressing_mode> void Executor::pe
#define next8() memory_[(program_counter_ + 1) & 0x1fff]
#define next16() (memory_[(program_counter_ + 1) & 0x1fff] | (memory_[(program_counter_ + 2) & 0x1fff] << 8))
// Underlying assumption below: the instruction stream will never
// overlap with IO ports.
switch(addressing_mode) {
// Addressing modes with no further memory access.
@ -53,22 +55,46 @@ template <Operation operation, AddressingMode addressing_mode> void Executor::pe
// Addressing modes with a memory access.
case AddressingMode::Absolute:
case AddressingMode::Absolute: address = next16(); break;
case AddressingMode::AbsoluteX: address = next16() + x_; break;
case AddressingMode::AbsoluteY: address = next16() + y_; break;
case AddressingMode::ZeroPage: address = next8(); break;
case AddressingMode::ZeroPageX: address = (next8() + x_) & 0xff; break;
case AddressingMode::ZeroPageY: address = (next8() + x_) & 0xff; break;
case AddressingMode::SpecialPage: address = 0x1f00 | next8(); break;
case AddressingMode::ZeroPageIndirect:
address = next8();
address = memory_[address] | (memory_[(address + 1) & 0xff] << 8);
break;
case AddressingMode::XIndirect:
address = (next8() + x_) & 0xff;
address = memory_[address] | (memory_[(address + 1)&0xff] << 8);
break;
case AddressingMode::IndirectY:
address = (memory_[next8()] | (memory_[(next8()+1)&0xff] << 8)) + y_;
break;
case AddressingMode::Relative:
address = program_counter_ + size(addressing_mode) + int8_t(next8());
break;
case AddressingMode::AbsoluteIndirect:
address = next16();
program_counter_ += 3;
address = memory_[address] | (memory_[(address + 1) & 0x1fff] << 8);
break;
case AddressingMode::AbsoluteX:
address = next16() + x_;
program_counter_ += 3;
break;
case AddressingMode::AbsoluteY:
address = next16() + y_;
program_counter_ += 3;
break;
/* TODO:
/* TODO: the rest. */
ImmediateZeroPage (for LDM)
BitXAccumulator
BitXZeroPage
BitXAccumulatorRelative
BitXZeroPageRelative
*/
default:
assert(false);
@ -77,6 +103,7 @@ template <Operation operation, AddressingMode addressing_mode> void Executor::pe
#undef next16
#undef next8
program_counter_ += 1 + size(addressing_mode);
assert(access_type(operation) != AccessType::None);
if constexpr(access_type(operation) == AccessType::Read) {