Xilinx MicroBlaze Reference Manual page 279

sb Store Byte
rD, rA, rB
sb
sbr rD, rA, rB
rD, rA, rB
sbea
1 1 0 1 0 0
0
6
Description
Stores the contents of the least significant byte of register rD, into the memory location that results
from adding the contents of registers rA and rB.
If the R bit is set, a byte reversed memory location is used, storing data with the opposite endianness
of the endianness defined by the E bit (if virtual protected mode is enabled).
If the EA bit is set, an extended address is used, formed by concatenating rA and rB instead of adding
them.
A data TLB miss exception occurs if virtual protected mode is enabled, and a valid translation entry
corresponding to the address is not found in the TLB.
A data storage exception occurs if virtual protected mode is enabled, and access is prevented by no-
access-allowed or read-only zone protection. No-access-allowed can only occur in user mode.
A privileged instruction error occurs if the EA bit is set, Physical Address Extension (PAE) is enabled,
and the instruction is not explicitly allowed.
Pseudocode
if EA = 1 then
← (
Addr rA) & (rB)
else
←
Addr (rA) + (rB)
if TLB_Miss(Addr) and MSR[VM] = 1 then
←
ESR[EC] 10010;ESR[S]
←
MSR[UMS]
else if Access_Protected(Addr) and MSR[VM] = 1 then
←
ESR[EC]
←
MSR[UMS]
else
← (
Mem(Addr)
Registers Altered
• MSR[UM], MSR[VM], MSR[UMS], MSR[VMS], if an exception is generated
• ESR[EC], ESR[S], if an exception is generated
• ESR[DIZ], if a data storage exception is generated
MicroBlaze Processor Reference Guide
UG984 (v2018.2) June 21, 2018
rD rA
11
←
1
←
MSR[UM]; MSR[VMS]
←
10000;ESR[S] 1; ESR[DIZ]
←
MSR[UM]; MSR[VMS] MSR[VM]; MSR[UM]
rD)[24:31]
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Chapter 5: MicroBlaze Instruction Set Architecture
rB 0 R 0 EA 0 0 0 0 0 0 0
16 21
←
MSR[VM]; MSR[UM] 0; MSR[VM]
←
No-access-allowed
←
0; MSR[VM]
31
←
0
←
0
280
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