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104 www.xilinx.com MicroBlaze Processor Reference Guide
1-800-255-7778 UG081 (v6.0) June 1, 2006
Chapter 4: MicroBlaze Instruction Set Architecture
R
fcmp
Floating Point Number Comparison
Description
The floating point value in rB is compared with the floating point value in rA and the
comparison result is placed into register rD. The OpSel field in the instruction code
determines the type of comparison performed.
Pseudocode
if isDnz(rA) or isDnz(rB) then
(rD) ← 0
FSR[DO] ← 1
ESR[EC] ← 00110
else
{read out behavior from Table 4-2}
fcmp.un
rD, rA, rB Unordered floating point comparison
fcmp.lt
rD, rA, rB Less-than floating point comparison
fcmp.eq
rD, rA, rB Equal floating point comparison
fcmp.le
rD, rA, rB Less-or-Equal floating point comparison
fcmp.gt
rD, rA, rB Greater-than floating point comparison
fcmp.ne
rD, rA, rB Not-Equal floating point comparison
fcmp.ge
rD, rA, rB Greater-or-Equal floating point comparison
0 1 0 1 1 0 rD rA rB 0 1 0 0 OpSel 0 0 0 0
0 6 11 16 21 25 28 31
Table 4-2: Floating Point Comparison Operation
Comparison Type Operand Relationship
Description OpSel (rB) > (rA) (rB) < (rA) (rB) = (rA) isNaN(rA) or isNaN(rB)
Unordered 000
(rD) ← 0 (rD) ← 0 (rD) ← 0 (rD) ← 1
Less-than 001
(rD) ← 0 (rD) ← 1 (rD) ← 0 (rD) ← 0
FSR[IO] ← 1
ESR[EC] ← 00110
Equal 010
(rD) ← 0 (rD) ← 0 (rD) ← 1 (rD) ← 0
Less-or-equal 011
(rD) ← 0 (rD) ← 1 (rD) ← 1 (rD) ← 0
FSR[IO] ← 1
ESR[EC] ← 00110