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fix SBC bug in thumb (same bug as the one normatt fixed in arm in r923)

This commit is contained in:
zeromus 2008-12-31 09:50:11 +00:00
parent 2cc03b0a97
commit 850882cf01
2 changed files with 5 additions and 12 deletions
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5
desmume/src/arm_instructions.cpp
View File

@ -22,11 +22,6 @@
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
//zero 9/8/08 - fixed a bug
//SIGNED_UNDERFLOW(a, (!cpu->CPSR.bits.C), tmp)
//was being called. but SIGNED_UNDERFLOW expects values in bit31. replaced with
//SIGNED_UNDERFLOW(a, (cpu->CPSR.bits.C?0:0x80000000), tmp)
#include "cp15.h"
#include "debug.h"
#include "MMU.h"

12
desmume/src/thumb_instructions.cpp
View File

@ -24,11 +24,6 @@
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
//zero 9/8/08 - fixed a bug
//SIGNED_UNDERFLOW(a, (!cpu->CPSR.bits.C), tmp)
//was being called. but SIGNED_UNDERFLOW expects values in bit31. replaced with
//SIGNED_UNDERFLOW(a, (cpu->CPSR.bits.C?0:0x80000000), tmp)
#include "bios.h"
#include "debug.h"
#include "MMU.h"
@ -357,8 +352,11 @@ TEMPLATE static u32 FASTCALL OP_SBC_REG()
cpu->CPSR.bits.N = BIT31(res);
cpu->CPSR.bits.Z = res == 0;
cpu->CPSR.bits.C = (!UNSIGNED_UNDERFLOW(a, (u32)(cpu->CPSR.bits.C?0:0x80000000), tmp)) & (!UNSIGNED_OVERFLOW(tmp, b, res));
cpu->CPSR.bits.V = SIGNED_UNDERFLOW(a, (u32)(cpu->CPSR.bits.C?0:0x80000000), tmp) | SIGNED_OVERFLOW(tmp, b, res);
//zero 31-dec-2008 - apply normatt's fixed logic from the arm SBC instruction
//although it seemed a bit odd to me and to whomever wrote this for SBC not to work similar to ADC..
//but thats how it is.
cpu->CPSR.bits.C = !UNSIGNED_UNDERFLOW(a, b, res);
cpu->CPSR.bits.V = SIGNED_UNDERFLOW(a, b, res);
return 3;
}