DSP Core Reference Manual

LSRA
SC140 DSP Core Reference Manual A-227
LSRA Bitwise Shift Right By One Bit (AGU) LSRA
Description
Status and Conditions that Affect Instruction
Status and Conditions Changed by Instruction
None.
Example
lsra r2
Instruction Formats and Opcodes
Instruction Fields
Rx RRRR AGU Source/Destination Register
Operation Assembler Syntax
(Rx>>>1) → Rx; 0 → Rx[31]
LSRA Rx
LSRA Rx
Shifts the contents of an AGU register (Rx) right one bit. Bits [31:1] are copied to bits [30:0]. Bit 31 is
cleared.
Register Address Bit Name Description
SR[18] EXP Determines which stack pointer is used when the stack pointer is an
operand. Otherwise, the instruction is not affected by SR.
Register/Memory Address Before After
R2
$AAAA AAAA $5555 5555
Instruction Words Cycles Type Opcode
15 8 7 0
LSRA Rx 1 1 2 1 1 1 0RRRR11111111
0000 N0 0100 — 1000 R0 1100 R4
0001 N1 0101 — 1001 R1 1101 R5
0010 N2 0110 — 1010 R2 1110 R6
0011 N3 0111 SP 1011 R3 1111 R7
Note: This instruction can specify R8-R15 as operands by using a high register prefix.