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fixed add/sub overflow/carry flags

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This commit is contained in:
Michaël Banaan Ananas 2012-07-15 13:49:52 +00:00
parent 300f35836a
commit 1245af36c3
1 changed files with 28 additions and 70 deletions
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98
src/emu/cpu/tms32051/32051ops.c
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@ -13,46 +13,32 @@ INLINE UINT16 POP_STACK(tms32051_state *cpustate)
return pc; return pc;
} }
INLINE INT32 SUB(tms32051_state *cpustate, INT32 a, INT32 b, int shift16) INLINE INT32 SUB(tms32051_state *cpustate, UINT32 a, UINT32 b, int shift16)
{
UINT32 res = a - b;
// check overflow
if ((a ^ b) & (a ^ res) & 0x80000000)
{ {
INT64 res = a - b;
if (cpustate->st0.ovm) // overflow saturation mode if (cpustate->st0.ovm) // overflow saturation mode
{ {
if ((res & 0x80000000) && ((UINT32)(res >> 32) & 0xffffffff) != 0xffffffff) res = ((INT32)(res) < 0) ? 0x7fffffff : 0x80000000;
{
res = 0x80000000;
} }
else if (((res & 0x80000000) == 0) && ((UINT32)(res >> 32) & 0xffffffff) != 0)
{ // set OV, this is a sticky flag
res = 0x7fffffff;
}
}
else // normal mode, result is not modified
{
// set OV flag if overflow occurred, this is a sticky flag
if (((a) ^ (b)) & ((a) ^ ((INT32)res)) & 0x80000000)
{
cpustate->st0.ov = 1; cpustate->st0.ov = 1;
} }
}
// set carry // set carry
if (!shift16) if (!shift16)
{ {
// C is cleared if borrow was generated // C is cleared if borrow was generated
if (((UINT64)(a) + (UINT64)(~b)) & U64(0x100000000)) cpustate->st1.c = (b > a) ? 0 : 1;
{
cpustate->st1.c = 0;
}
else
{
cpustate->st1.c = 1;
}
} }
else else
{ {
// if 16-bit shift, C is cleared if borrow was generated, otherwise C is unaffected // if 16-bit shift, C is cleared if borrow was generated, otherwise C is unaffected
if (((UINT64)(a) + (UINT64)(~b)) & U64(0x100000000)) if (b > a)
{ {
cpustate->st1.c = 0; cpustate->st1.c = 0;
} }
@ -61,46 +47,32 @@ INLINE INT32 SUB(tms32051_state *cpustate, INT32 a, INT32 b, int shift16)
return (INT32)(res); return (INT32)(res);
} }
INLINE INT32 ADD(tms32051_state *cpustate, INT32 a, INT32 b, int shift16) INLINE INT32 ADD(tms32051_state *cpustate, UINT32 a, UINT32 b, int shift16)
{
UINT32 res = a + b;
// check overflow
if ((a ^ res) & (b ^ res) & 0x80000000)
{ {
INT64 res = a + b;
if (cpustate->st0.ovm) // overflow saturation mode if (cpustate->st0.ovm) // overflow saturation mode
{ {
if ((res & 0x80000000) && ((UINT32)(res >> 32) & 0xffffffff) != 0xffffffff) res = ((INT32)(res) < 0) ? 0x7fffffff : 0x80000000;
{
res = 0x80000000;
}
else if (((res & 0x80000000) == 0) && ((UINT32)(res >> 32) & 0xffffffff) != 0)
{
res = 0x7fffffff;
}
}
else // normal mode, result is not modified
{
// set OV flag if overflow occurred, this is a sticky flag
if (((res) ^ (b)) & ((res) ^ (a)) & 0x80000000)
{
cpustate->st0.ov = 1;
}
} }
// set carry // set OV, this is a sticky flag
cpustate->st0.ov = 1;
}
// check carry
if (!shift16) if (!shift16)
{ {
// C is set if carry was generated // C is set if carry was generated
if (res & U64(0x100000000)) cpustate->st1.c = (((UINT64)(a) + (UINT64)(b)) & U64(0x100000000)) ? 1 : 0;
{
cpustate->st1.c = 1;
}
else
{
cpustate->st1.c = 0;
}
} }
else else
{ {
// if 16-bit shift, C is set carry was generated, otherwise C is unaffected // if 16-bit shift, C is set carry was generated, otherwise C is unaffected
if (res & U64(0x100000000)) if (((UINT64)(a) + (UINT64)(b)) & U64(0x100000000))
{ {
cpustate->st1.c = 1; cpustate->st1.c = 1;
} }
@ -600,27 +572,13 @@ static void op_neg(tms32051_state *cpustate)
if ((UINT32)(cpustate->acc) == 0x80000000) if ((UINT32)(cpustate->acc) == 0x80000000)
{ {
cpustate->st0.ov = 1; cpustate->st0.ov = 1;
if (cpustate->st0.ovm) cpustate->st1.c = 0;
{ cpustate->acc = (cpustate->st0.ovm) ? 0x7fffffff : 0x80000000;
cpustate->acc = 0x7fffffff;
}
else
{
cpustate->acc = 0x80000000;
}
} }
else else
{ {
cpustate->acc = 0 - (UINT32)(cpustate->acc); cpustate->acc = 0 - (UINT32)(cpustate->acc);
cpustate->st1.c = (cpustate->acc == 0) ? 1 : 0;
if (cpustate->acc == 0)
{
cpustate->st1.c = 1;
}
else
{
cpustate->st1.c = 0;
}
} }
CYCLES(1); CYCLES(1);