
TM1100 Preliminary Data Book
Philips Semiconductors
A-88
PRELIMINARY INFORMATION
File: ops.fm5, modified 7/23/99
Convert oating-point to integer with round
toward zero
SYNTAX
[ IF r
guard ] ifixrz rsrc1
→ rdest
FUNCTION
if r
guard then {
r
dest
← (long) ((oat)rsrc1)
}
ATTRIBUTES
Function unit
falu
Operation code
21
Number of operands
1
Modier
No
Modier range
—
Latency
3
Issue slots
1, 4
DESCRIPTION
The ifixrz operation converts the single-precision IEEE oating-point value in r
src1 to a signed integer and
writes the result into r
dest. Rounding toward zero is performed; the IEEE rounding mode bits in PCSW are ignored.
This is the preferred rounding for ANSI C. If r
src1 is denormalized, zero is substituted before conversion, and the IFZ
ag in the PCSW is set. If ifixrz causes an IEEE exception, such as overow or underow, the corresponding
exception ags in the PCSW are set. The PCSW exception ags are sticky: the ags can be set as a side-effect of any
oating-point operation but can only be reset by an explicit writepcsw operation. The update of the PCSW
exception ags occurs at the same time as r
dest is written. If any other oating-point compute operations update the
PCSW at the same time, the net result in each exception ag is the logical OR of all simultaneous updates ORed with
the existing PCSW value for that exception ag.
The ifixrzflags operation computes the exception ags that would result from an individual ifixrz.
The ifixrz operation optionally takes a guard, specied in r
guard. If a guard is present, its LSB controls the
modication of the destination register. If the LSB of r
guard is 1, rdest and the exception ags in PCSW are written;
otherwise, r
dest is not changed and the operation does not affect the exception ags in PCSW.
EXAMPLES
Initial Values
Operation
Result
r30 = 0x40400000 (3.0)
ifixrz r30
→ r100
r100
← 3
r35 = 0x40247ae1 (2.57)
ifixrz r35
→ r102
r102
← 2, INX ag set
r10 = 0,
r40 = 0xff4fffff (–3.402823466e+38)
IF r10 ifixrz r40
→ r105
no change, since guard is false
r20 = 1,
r40 = 0xff4fffff (–3.402823466e+38)
IF r20 ifixrz r40
→ r110
r110
← 0x80000000 (-231), INV ag
set
r45 = 0x7f800000 (+INF))
ifixrz r45
→ r112
r112
← 0x7fffffff (231-1), INV ag set
r50 = 0xbfc147ae (-1.51)
ifixrz r50
→ r115
r115
← -1, INX ag set
r60 = 0x00400000 (5.877471754e-39)
ifixrz r60
→ r117
r117
← 0, IFZ set
r70 = 0xffffffff (QNaN)
ifixrz r70
→ r120
r120
← 0, INV ag set
r80 = 0xffbfffff (SNaN)
ifixrz r80
→ r122
r122
← 0, INV ag set
SEE ALSO
ixrz