Intel NIOS II Owner Reference Manual page 20

Related Information
Nios II Custom Instruction User Guide
2.3.3.1. Nios II Floating Point Hardware 2 Component
Table 3. Floating Point Custom Instruction 2 Operation Summary
In this table, a and b are assumed to be single-precision floating-point values.
(3) (4)
Operation N
fdivs 255
fsubs 254
fadds 253
fmuls 252
fsqrts 251
floatis 250
fixsi 249
round 248
Reserved 234 to 247
fmins 233
fmaxs 232
fcmplts 231
fcmples 230
fcmpgts 229
fcmpges 228
fcmpeqs 227
fcmpnes 226
fnegs 225
fabss 224
(3)
These names match the names of the corresponding GCC command-line options except for
round, which GCC does not support.
(4)
Specifies the 8 bit fixed custom instruction for the operation.
(5)
Nios II GCC version 4.7.3 is not able to reliably replace calls to newlib floating-point functions
with the equivalent custom instruction even though it has Flush to 0
command-line options and pragma support for these operations. Instead, the custom
instruction must be invoked directly using the GCC
Floating Point Custom Instruction 2 component includes a C header file that provides the
required
#define
Nios II Processor Reference Guide
20
Cycles
16 a ÷ b
5 a – b
5 a + b
4 a x b
8 a
4 int_to_float(a)
2 float_to_int(a)
2 float_to_int(a)
Undefined Undefined
1 (a < b) ? a : b
1 (a < b) ? b : a
1 (a < b) ? 1 : 0
1 (a ≤ b) ? 1 : 0
1 (a > b) ? 1 : 0
1 (a ≥ b) ? 1 : 0
1 (a = b) ? 1 : 0
1 (a ≠ b) ? 1 : 0
1 -a
1 |a|
macros to invoke the custom instruction directly.
Result Subnormal
Flush to 0
Flush to 0
Flush to 0
Flush to 0
Not applicable
Flush to 0
Flush to 0
Supported
Supported
Supported
Supported
Supported
Supported
Supported
Supported
Supported
Supported
__builtin_custom_*
2. Processor Architecture
NII-PRG | 2018.04.18
Rounding GCC
Inference
Nearest a / b
Faithful a – b
Faithful a + b
Faithful a * b
(5)
Faithful sqrtf()
Not applicable Casting
Truncation Casting
(5)
Nearest lroundf()
(5)
None fminf()
(5)
None fmaxf()
None a < b
None a <= b
None a > b
None a >= b
None a == b
None a != b
None -a
None fabsf()
<operation>
-mcustom-
facility. The