From 21ac9363e918e2af9a84d213f0f44803588292ce Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 11 Apr 2022 16:32:57 -0400
Subject: [PATCH] Add page 8.
---
InstructionSets/68k/Decoder.cpp | 25 ++++++++++++++++++++++++-
InstructionSets/68k/Decoder.hpp | 1 +
2 files changed, 25 insertions(+), 1 deletion(-)
diff --git a/InstructionSets/68k/Decoder.cpp b/InstructionSets/68k/Decoder.cpp
index bd10e0626..b4c201c23 100644
--- a/InstructionSets/68k/Decoder.cpp
+++ b/InstructionSets/68k/Decoder.cpp
@@ -113,8 +113,9 @@ template <Operation operation> Preinstruction Predecoder::decode(uint16_t instru
}
//
- // MARK: MULU, MULS.
+ // MARK: MULU, MULS, DIVU, DIVS.
//
+ case Operation::DIVU: case Operation::DIVS:
case Operation::MULU: case Operation::MULS:
return Preinstruction(operation,
ea_combined_mode, ea_register,
@@ -125,6 +126,27 @@ template <Operation operation> Preinstruction Predecoder::decode(uint16_t instru
// MARK: - Page decoders.
+Preinstruction Predecoder::decode8(uint16_t instruction) {
+ // 4-171 (p275)
+ if((instruction & 0x1f0) == 0x100) return decode<Operation::SBCD>(instruction);
+
+ // 4-150 (p254)
+ switch(instruction & 0x0c0) {
+ case 0x00: return decode<Operation::ORb>(instruction);
+ case 0x40: return decode<Operation::ORw>(instruction);
+ case 0x80: return decode<Operation::ORl>(instruction);
+ default: break;
+ }
+
+ switch(instruction & 0x1c0) {
+ case 0x0c0: return decode<Operation::DIVU>(instruction); // 4-97 (p201)
+ case 0x1c0: return decode<Operation::DIVS>(instruction); // 4-93 (p197)
+ default: break;
+ }
+
+ return Preinstruction();
+}
+
Preinstruction Predecoder::decodeC(uint16_t instruction) {
// 4-3 (p107)
if((instruction & 0x1f0) == 0x100) return decode<Operation::ABCD>(instruction);
@@ -157,6 +179,7 @@ Preinstruction Predecoder::decodeC(uint16_t instruction) {
Preinstruction Predecoder::decode(uint16_t instruction) {
// Divide first based on line.
switch(instruction & 0xf000) {
+ case 0x8000: return decode8(instruction);
case 0xc000: return decodeC(instruction);
default: break;
diff --git a/InstructionSets/68k/Decoder.hpp b/InstructionSets/68k/Decoder.hpp
index 06f450e32..d9bd2e86c 100644
--- a/InstructionSets/68k/Decoder.hpp
+++ b/InstructionSets/68k/Decoder.hpp
@@ -26,6 +26,7 @@ class Predecoder {
private:
// Page by page decoders; each gets a bit ad hoc so
// it is neater to separate them.
+ Preinstruction decode8(uint16_t instruction);
Preinstruction decodeC(uint16_t instruction);
// Specific instruction decoders.