
Philips Semiconductors
DSPCPU Operations for TM1300
PRODUCT SPECIFICATION
A-91
Convert signed integer to oating-point
SYNTAX
[ IF r
guard ] ifloat rsrc1
→ rdest
FUNCTION
if r
guard then {
r
dest
← (oat) ((long)rsrc1)
}
ATTRIBUTES
Function unit
falu
Operation code
20
Number of operands
1
Modier
No
Modier range
—
Latency
3
Issue slots
1, 4
DESCRIPTION
The ifloat operation converts the signed integer value in r
src1 to single-precision IEEE oating-point format and
writes the result into r
dest. Rounding is according to the IEEE rounding mode bits in PCSW. If ifloat causes an
IEEE exception, such as inexact, 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 ifloatflags operation computes the exception ags that would result from an individual ifloat.
The ifloat 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 = 3
ifloat r30
→ r100
r100
← 0x40400000 (3.0)
r40 = 0xffffffff (-1)
ifloat r40
→ r105
r105
← 0xbf800000 (-1.0)
r10 = 0, r50 = 0xfffffffd
IF r10 ifloat r50
→ r110
no change, since guard is false
r20 = 1, r50 = 0xfffffffd
IF r20 ifloat r50
→ r115
r115
← 0xc0400000 (–3.0)
r60 = 0x7fffffff (2147483647)
ifloat r60
→ r117
r117
← 0x4f000000 (2.147483648e+9), INX ag set
r70 = 0x80000000 (-2147483648)
ifloat r70
→ r120
r120
← 0xcf000000 (-2.147483648e+9)
r80 = 0x7ffffff1 (2147483633)
ifloat r80
→ r122
r122
← 0x4f000000 (2.147483648e+9), INX ag set
SEE ALSO
ufloat ifloatrz ufloatrz
ifixieee ifloatflags
ifloat