MicroBlaze Processor Reference Guide
163
UG081 (v14.7)
Instructions
addi
Arithmetic Add Immediate
Description
The sum of the contents of registers rA and the value in the IMM field, sign-extended to 32 bits, is
placed into register rD. Bit 3 of the instruction (labeled as K in the figure) is set to one for the
mnemonic addik. Bit 4 of the instruction (labeled as C in the figure) is set to one for the mnemonic
addic. Both bits are set to one for the mnemonic addikc.
When an addi instruction has bit 3 set (addik, addikc), the carry flag will keep its previous value
regardless of the outcome of the execution of the instruction. If bit 3 is cleared (addi, addic), then the
carry flag will be affected by the execution of the instruction.
When bit 4 of the instruction is set to one (addic, addikc), the content of the carry flag (MSR[C])
affects the execution of the instruction. When bit 4 is cleared (addi, addik), the content of the carry
flag does not affect the execution of the instruction (providing a normal addition).
Pseudocode
if C = 0 then
(rD)
←
(rA) + sext(IMM)
else
(rD)
←
(rA) + sext(IMM) + MSR[C]
if K = 0 then
MSR[C]
←
CarryOut
Registers Altered
•
rD
•
MSR[C]
Latency
1 cycle
Notes
The C bit in the instruction opcode is not the same as the carry bit in the MSR.
By default, Type B Instructions take the 16-bit IMM field value and sign extend it to 32 bits to use
as the immediate operand. This behavior can be overridden by preceding the Type B instruction with
an imm instruction. See the instruction
for details on using 32-bit immediate
values.
addi
rD, rA, IMM
Add Immediate
addic
rD, rA, IMM
Add Immediate with Carry
addik
rD, rA, IMM
Add Immediate and Keep Carry
addikc
rD, rA, IMM
Add Immediate with Carry and Keep Carry
0 0 1 K C 0
rD
rA
IMM
0
6
1
1
1
6
3
1
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