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Fixes NBCD -(An)+, adds some additional comments.

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This commit is contained in:
Thomas Harte 2019-12-16 20:01:19 -05:00
parent ba2436206f
commit 8be26502c4
1 changed files with 7 additions and 4 deletions
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9
Processors/68000/Implementation/68000Storage.cpp
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@ -1874,6 +1874,7 @@ struct ProcessorStorageConstructor {
// Decodes the format used by ABCD and SBCD.
case Decoder::ABCD_SBCD: {
if(instruction & 8) {
// [A/S]BCD -(An), -(An)
program.set_source(storage_, Ind, ea_register);
program.set_destination(storage_, Ind, data_register);
@ -1881,6 +1882,7 @@ struct ProcessorStorageConstructor {
op(MicroOp::DestinationMask | dec(data_register), seq("nrd np", { a(data_register) }, false ));
op(Action::PerformOperation, seq("nw", { a(data_register) }, false));
} else {
// [A/S]BCD Dn, Dn
program.set_source(storage_, Dn, ea_register);
program.set_destination(storage_, Dn, data_register);
@ -2507,6 +2509,7 @@ struct ProcessorStorageConstructor {
program.set_destination(storage_, ea_mode, ea_register);
is_byte_access = operation == Operation::NBCD;
is_long_word_access = false;
const int mode = combined_mode(ea_mode, ea_register);
switch(mode) {
@ -2521,12 +2524,12 @@ struct ProcessorStorageConstructor {
op(Action::None, seq("nrd", { a(ea_register) }, !is_byte_access));
op(Action::PerformOperation, seq("np nw", { a(ea_register) }, !is_byte_access));
if(mode == PostInc) {
op(int(Action::Increment2) | MicroOp::DestinationMask);
op(inc(ea_register) | MicroOp::DestinationMask);
}
break;
case PreDec: // MOVE SR, -(An)
op(int(Action::Decrement2) | MicroOp::DestinationMask, seq("n nrd", { a(ea_register) }, !is_byte_access));
op(dec(ea_register) | MicroOp::DestinationMask, seq("n nrd", { a(ea_register) }, !is_byte_access));
op(Action::PerformOperation, seq("np nw", { a(ea_register) }, !is_byte_access));
break;
@ -2907,7 +2910,7 @@ struct ProcessorStorageConstructor {
}
break;
case PreDec: // CHK (An)-, Dn
case PreDec: // CHK -(An), Dn
op(int(Action::Decrement2) | MicroOp::SourceMask, seq("n nr np", { a(ea_register) }));
break;