Excalibur electronic A-MNL-NIOSPROG-01.1 ST8s, Movi %g4,12, Mem%g4 + 36 +, FILL8 %r0,%rX PFX Y

32-Bit Instruction Set

ST8s

Store 8-bit Data To Memory (Static Byte-Offset Address)

Operation:

Not preceded by PFX:

bnMem32[align32(RA)] ← bnR0 where n = IMM2

Preceded by PFX:

bnMem32[align32(RA + (σ(K) × 4))] ← bnR0 where n = IMM2

Assembler Syntax:

ST8s [%rA],%r0,IMM2

Example:

Not preceded by PFX:

MOVI %g4,12

ST8s [%g4],%r0,3 ; store high byte of %r0 to mem[15]

Preceded by PFX:

PFX 9

ST8s [%g4],%r0,2 ; store byte 2 of %r0 to

; mem[%g4 + 36 + 2]

Description:

Not preceded by PFX:

Stores one of the four bytes of %r0 to memory at the byte-address given by

(RA[31..2] plus IMM2). The two bits RA[1..0] are ignored. IMM2 selects which

byte of %r0 is stored (byte 3 is most significant).

ST8s may be used in combination with FILL8 to implement a byte-store operation

to a byte-offset from a word-aligned base pointer. Given a byte held in bits 7..0 of

any register %rX, the following sequence writes this byte to memory at the byte-

address given by (RA + Y )

(RA presumed to hold a word-aligned pointer):

FILL8 %r0,%rX

PFX Y >> 2

ST8s [%rA],%r0,Y & 3

Preceded by PFX:

A 13-bit signed, byte-scaled offset is formed by concatenating K with IMM2. This

offset (K : IMM2) is sign-extended to 32 bits and used as the byte-offset for the

ST-operation.

Condition Codes:

Flags: Unaffected

N

V

Z

C

−

−

−

−

Instruction Format:

Ri2u

Instruction Fields:

A = Register index of operand RA

IMM2 = 2-bit immediate value

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

0

1

1

1

0

1

1

0

0

IMM2

A

94 Altera Corporation