6502/CLK
1
0
Fork 0
mirror of https://github.com/TomHarte/CLK.git synced 2024-07-09 06:29:33 +00:00
Code Issues Projects Releases Wiki Activity

Make first attempt to complete broad phase of decoding.

Browse Source
This commit is contained in:
Thomas Harte 2022-04-12 09:08:46 -04:00
parent cd465dd121
commit e7f6cc598d
1 changed files with 12 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
InstructionSets/68k/Decoder.cpp
View File

@ -308,18 +308,17 @@ Preinstruction Predecoder::decode4(uint16_t instruction) {
switch(instruction & 0xff0) {
case 0xe40: return decode<Operation::TRAP>(instruction); // 4-188 (p292)
// case 0xe60: return decode<Operation::MOVEtoUSP>(instruction); // 6-21 (p475)
default: break;
}
// TODO: determine MOVEtoUSP and MOVEfromUSP.
switch(instruction & 0xff8) {
case 0xe60: return decode<Operation::SWAP>(instruction); // 4-185 (p289)
case 0x860: return decode<Operation::SWAP>(instruction); // 4-185 (p289)
case 0x880: return decode<Operation::EXTbtow>(instruction); // 4-106 (p210)
case 0x8c0: return decode<Operation::EXTwtol>(instruction); // 4-106 (p210)
case 0xe50: return decode<Operation::LINK>(instruction); // 4-111 (p215)
case 0xe58: return decode<Operation::UNLINK>(instruction); // 4-194 (p298)
case 0xe60: return decode<Operation::MOVEtoUSP>(instruction); // 6-21 (p475)
case 0xe68: return decode<Operation::MOVEfromUSP>(instruction); // 6-21 (p475)
default: break;
}
@ -441,11 +440,13 @@ Preinstruction Predecoder::decodeB(uint16_t instruction) {
}
Preinstruction Predecoder::decodeC(uint16_t instruction) {
// 4-3 (p107)
if((instruction & 0x1f0) == 0x100) return decode<Operation::ABCD>(instruction);
switch(instruction & 0x1f0) {
case 0x100: return decode<Operation::ABCD>(instruction); // 4-3 (p107)
default: break;
}
// 4-15 (p119)
switch(instruction & 0x0c0) {
// 4-15 (p119)
case 0x00: return decode<Operation::ANDb>(instruction);
case 0x40: return decode<Operation::ANDw>(instruction);
case 0x80: return decode<Operation::ANDl>(instruction);
@ -463,6 +464,7 @@ Preinstruction Predecoder::decodeC(uint16_t instruction) {
case 0x140:
case 0x148:
case 0x188: return decode<Operation::EXG>(instruction);
default: break;
}
return Preinstruction();
@ -471,9 +473,9 @@ Preinstruction Predecoder::decodeC(uint16_t instruction) {
Preinstruction Predecoder::decodeD(uint16_t instruction) {
switch(instruction & 0x0c0) {
// 4-4 (p108)
case 0x00: return decode<Operation::ADDb>(instruction);
case 0x40: return decode<Operation::ADDw>(instruction);
case 0x80: return decode<Operation::ADDl>(instruction);
case 0x000: return decode<Operation::ADDb>(instruction);
case 0x040: return decode<Operation::ADDw>(instruction);
case 0x080: return decode<Operation::ADDl>(instruction);
default: break;
}