Skip to content

Fix EXG instruction exception #337

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Jun 6, 2025
+11 −3
Merged

Fix EXG instruction exception #337

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
14 changes: 11 additions & 3 deletions mc6809.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -117,6 +117,8 @@ void MC6809Init(void)
xfreg16[3]=&U_REG;
xfreg16[4]=&S_REG;
xfreg16[5]=&PC_REG;
xfreg16[6] = 0;
xfreg16[7] = 0;

ureg8[0]=(unsigned char*)&A_REG;
ureg8[1]=(unsigned char*)&B_REG;
Expand Down Expand Up @@ -490,9 +492,15 @@ void Do_Opcode(int CycleFor)
}
else // 16 bit EXG
{
temp16=(*xfreg16[((postbyte & 0x70) >> 4)]);
(*xfreg16[((postbyte & 0x70) >> 4)])=(*xfreg16[postbyte & 0x07]);
(*xfreg16[postbyte & 0x07])=temp16;
uint16_t* src = xfreg16[((postbyte & 0x70) >> 4)];
uint16_t* dest = xfreg16[postbyte & 0x07];
// todo: find out which program triggers it
assert(src);
assert(dest);
uint16_t srcValue = src ? *src : 0xFFFF;
uint16_t destValue = dest ? *dest : 0xFFFF;
if (src) *src = destValue;
if (dest) *dest = srcValue;
}
}
setcc(ccbits);
Expand Down