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110 www.xilinx.com PicoBlaze 8-bit Embedded Microcontroller
UG129 (v1.1.2) June 24, 2008
Appendix : PicoBlaze Instruction Set and Event Reference
R
Examples
SL0 sX; Shift left. 0 shifts into LSB, MSB shifts into CARRY.
SL1 sX; Shift left. 1 shifts into LSB, MSB shifts into CARRY.
SLX sX; Shift left. LSB shifts into LSB, MSB shifts into CARRY.
SLA sX; Shift left. CARRY shifts into LSB, MSB shifts into CARRY.
Pseudocode
case (INSTRUCTION)
when “SL0”
LSB Å 0
when “SL1”
LSB Å 1
when “SLX”
LSB Å sX(7)
when “SLA”
LSB Å CARRY
end case
CARRY Å sX[7]
sX Å {sX[6:0], LSB}
if ( sX = 0 ) then
ZERO Å 1
else
ZERO Å 0
endif
PC Å PC + 1
Registers/Flags Altered
Registers: sX, PC
Flags: CARRY, ZERO
SR[ 0 | 1 | X | A ] sX — Shift Right Register sX
There are four variants of the shift right instruction, as shown in Table C-8, that operate on
any single data register. Each bit in the specified register is shifted right by one bit position.
The least-significant bit, bit 0, shifts into the CARRY bit. The last character of the
instruction mnemonic—i.e., ‘0’, ‘1’, ‘X’, or ‘A’—indicates the value shifted into the most-
significant bit, bit 7.