CL-PS7500FE View Datasheet(PDF) - Cirrus Logic

Part Name

Description

Manufacturer

CL-PS7500FE

System-on-a Chip for Internet Appliance

Cirrus Logic 

CL-PS7500FE

System-on-a-Chip for Internet Appliance

WFS,RFS,WFC, and RFC

efgh

these bits are reserved and should be zero.

Constants

Constants cannot be specified in the Fm field for the FIX instruction, as there is no point FIXing a known

value into an ARM integer register; it would be quicker to use a MOV instruction.

19.3.1 Compare Operations

31

28 27

24 23 22 21 20 19

16 15

12 11

87

43

0

cond

1110

abc

1

e Fn

1111

0001

fgh1

i Fm

NOTE: These are special cases of the general CPRT instruction, with Rd = 15 and L/S = 1.

<CMF|CNF|CMFE|CNFE>{cond} Fn, Fm

abc

operation

i

constant ROM/Fm (see Section 19.2)

efgh

are reserved and should be ‘0’

abc Mnemonic Description

100 CMF

Compare floating

101 CNF

Compare negated floating

110 CMFE

Compare floating with exception

111 CNFE

Compare negated floating with exception

Operation

compare Fn with Fm

compare Fn with -Fm

compare Fn with Fm

compare Fn with -Fm

Compares

Compares are provided with and without the exception that could arise if the numbers are unordered.

When testing IEEE predicates, the CMF instruction should be used to test for equality (that is, when a

BEQ or BNE is used afterwards) or to test for unorderedness (in the V flag). The CMFE instruction should

be used for all other tests (BGT, BGE, BLT, and BLE afterwards). CMFE produces an exception if the num-

bers are unordered (whenever at least one operand is a NaN). CMF only produces an exception when at

least one operand is a signalling NaN.

The ARM flags N, Z, C, and V refer to Table 19-4 after compares.

Table 19-4. Flag Settings When the AC Bit in the FPSR is Clear

Flag

N

Z

C

V

Description

Example

Less Than

Fn less than Fm (or -Fm)

Equal

Greater Than or Equal Fn greater than or equal to Fm

Unordered

NOTE: That when two numbers are not equal N and C are not necessarily opposites: if the result is unordered they

are both false.

June 1997

ADVANCE DATA BOOK v2.0

FLOATING-POINT INSTRUCTION SET

179

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