|
|
@@ -151,44 +151,47 @@
|
|
|
// (r3:r4) = (r3:r4) * (r5:r6), checkoverflow is in r7
|
|
|
// res f1 f2
|
|
|
|
|
|
- or. r8,r3,r5 // are both msw's 0?
|
|
|
+ or. r10,r3,r5 // are both msw's 0?
|
|
|
mulhwu r8,r4,r6 // msw of product of lsw's
|
|
|
+ subi r0,r7,1 // if no overflowcheck, r0 := $ffffffff, else r0 := 0;
|
|
|
+ beq .LDone // if both msw's are zero, skip cross products
|
|
|
+ mullw r9,r4,r5 // lsw of first cross-product
|
|
|
cntlzw r11,r3 // count leading zeroes of msw1
|
|
|
cntlzw r12,r5 // count leading zeroes of msw2
|
|
|
- subi r0,r7,1 // if no overflowcheck, r0 := $ffffffff, else r0 := 0;
|
|
|
+ mullw r7,r3,r6 // lsw of second cross-product
|
|
|
+ add r12,r11,r12 // sum of leading zeroes
|
|
|
mr r10,r8
|
|
|
- add r9,r11,r12 // sum of leading zeroes
|
|
|
- or r0,r9,r0 // maximise sum if no overflow checking, otherwise it remains
|
|
|
+ add r8,r8,r9 // add
|
|
|
+ or r0,r12,r0 // maximise sum if no overflow checking, otherwise it remains
|
|
|
cmplwi cr1,r0,64 // >= 64 leading zero bits in total? If so, no overflow
|
|
|
- beq .Lmsw_zero // if both msw's are zero, skip cross products
|
|
|
- mullw r7,r3,r6 // lsw of first cross-product
|
|
|
add r8,r8,r7 // add
|
|
|
- mullw r5,r4,r5 // lsw of second cross-product
|
|
|
- add r8,r8,r5 // add
|
|
|
- .Lmsw_zero:
|
|
|
bge+ cr1,.LDone // if the sum of leading zero's >= 64 (or checkoverflow was 0)
|
|
|
// there's no overflow, otherwise more thorough check
|
|
|
+ add r7,r7,r9
|
|
|
+ mulhwu r3,r6,r3
|
|
|
+ addc r7,r7,r10 // add the msw of the product of the lsw's, record carry
|
|
|
+ cntlzw r9,r5
|
|
|
+ cntlzw r10,r4 // get leading zeroes count of lsw f1
|
|
|
+ mulhwu r5,r4,r5
|
|
|
+ addze r3,r3
|
|
|
subfic r0,r11,31 // if msw f1 = 0, then r0 := -1, else r0 >= 0
|
|
|
- cntlzw r3,r4 // get leading zeroes count of lsw f1
|
|
|
+ cntlzw r7,r6
|
|
|
+ subfic r11,r9,31 // same for f2
|
|
|
srawi r0,r0,31 // if msw f1 = 0, then r0 := 1, else r0 := 0
|
|
|
- subfic r11,r12,31 // same for f2
|
|
|
- cntlzw r12,r6
|
|
|
srawi r11,r11,31
|
|
|
- and r3,r3,r0 // if msw f1 <> 0, the leading zero count lsw f1 := 0
|
|
|
- and r12,r12,r11 // same for f2
|
|
|
- add r9,r9,r3 // add leading zero counts of lsw's to sum if appropriate
|
|
|
+ and r10,r10,r0 // if msw f1 <> 0, the leading zero count lsw f1 := 0
|
|
|
+ and r9,r7,r11 // same for f2
|
|
|
+ or. r5,r5,r3
|
|
|
+ add r9,r9,r10 // add leading zero counts of lsw's to sum if appropriate
|
|
|
add r9,r9,r12
|
|
|
- cmplwi r9,64 // is the sum now >= 64?
|
|
|
+ cmplwi cr7,r9,64 // is the sum now >= 64?
|
|
|
cmplwi cr1,r9,62 // or <= 62?
|
|
|
- bge+ .LDone // >= 64 leading zeroes -> no overflow
|
|
|
+ bge+ cr7,.LDone // >= 64 leading zeroes -> no overflow
|
|
|
ble+ cr1,.LOverflow // <= 62 leading zeroes -> overflow
|
|
|
// for 63 zeroes, we need additional checks
|
|
|
- add r9,r7,r5 // sum of lsw's cross products can't produce a carry,
|
|
|
+ // sum of lsw's cross products can't have produced a carry,
|
|
|
// because the sum of leading zeroes is 63 -> at least
|
|
|
// one of these cross products is 0
|
|
|
- li r0, 0
|
|
|
- addc r9,r9,r10 // add the msw of the product of the lsw's
|
|
|
- addze. r0,r0
|
|
|
beq+ .LDone
|
|
|
.LOverflow:
|
|
|
b FPC_OVERFLOW
|
|
|
@@ -200,7 +203,10 @@
|
|
|
|
|
|
{
|
|
|
$Log$
|
|
|
- Revision 1.7 2005-02-14 17:13:31 peter
|
|
|
+ Revision 1.8 2005-02-19 14:16:02 jonas
|
|
|
+ * fixed overflow detection, + some small optimizations
|
|
|
+
|
|
|
+ Revision 1.7 2005/02/14 17:13:31 peter
|
|
|
* truncate log
|
|
|
|
|
|
}
|
Jonas Maebe