stswi or stsi (Store String Word Immediate) Instruction

Assembler Language Reference

stswi or stsi (Store String Word Immediate) Instruction

Purpose

Stores consecutive bytes from consecutive registers into a specified location in memory.

Syntax

PowerPC
stswi	RS,RA,NB

POWER
stsi	RS,RA,NB

Description

The stswi and stsi instructions store N consecutive bytes starting with the leftmost byte in general-purpose register (GPR) RS at the effective address (EA) from GPR RS through GPR RS + NR - 1.

If GPR RA is not 0, the EA is the contents of GPR RA. If RA is 0, then the EA is 0.

Consider the following when using the stswi and stsi instructions:

NB is the byte count.
RS is the starting register.
N is NB, which is the number of bytes to store. If NB is 0, then N is 32.
NR is ceiling(N/4), which is the number of registers to store data from.

For the POWER instruction stsi, the contents of the MQ Register are undefined.

The stswi and stsi instructions have one syntax form and do not affect the Fixed-Point Exception Register or Condition Register Field 0.

Parameters

RS	Specifies source general-purpose register of stored data.
RA	Specifies source general-purpose register for EA calculation.
NB	Specifies byte count for EA calculation.

Examples

The following code stores the bytes contained in GPR 6 to GPR 8 into a location in memory:

.csect data[rw]
buffer: .long 0,0,0
# Assume GPR 4 contains the address of buffer.
# Assume GPR 6 contains 0x4865 6C6C.
# Assume GPR 7 contains 0x6F20 776F.
# Assume GPR 8 contains 0x726C 6421.
.csect text[pr]
stswi 6,4,12
# buffer now contains 0x4865 6C6C 6F20 776F 726C 6421.

Related Information

Fixed-Point Processor .

Fixed-Point String Instructions .