7 DETAILS OF INSTRUCTIONS
7-74
EPSON
S1C17 FAMILY S1C17 CORE MANUAL
ld.a [%sp + imm7], %rs
Function
32-bit data transfer
Standard)
A[sp + imm7](23:0)
← rs(23:0), A[sp + imm7](31:24) ← 0
Extension 1) A[sp + imm20](23:0)
← rs(23:0), A[sp + imm20](31:24) ← 0
Extension 2) A[sp + imm24](23:0)
← rs(23:0), A[sp + imm24](31:24) ← 0
Code
15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
1 1 1 1 1 1
r s
imm7
|
Flag
IL IE
C
V
Z
N
– – – – – –
|
Mode
Src:Register direct %rs = %r0 to %r7
Dst:Register indirect with displacement
CLK
Two cycles
Description (1) Standard
ld.a
[%sp + imm7],%rs
; memory address = sp + imm7
The content of the rs register is transferred to the specified memory location. The content of
the current SP with the 7-bit immediate imm7 added as displacement comprises the memory
address to be accessed. This instruction writes 32-bit data with the eight high-order bits set to 0
in the memory.
(2) Extension 1
ext
imm13
; = imm20(19:7)
ld.a
[%sp + imm7],%rs
; memory address = sp + imm20,
; imm7 = imm20(6:0)
The ext instruction extends the displacement to a 20-bit quantity. As a result, the content of
the rs register is transferred to the address indicated by the content of the SP with the 20-bit
immediate imm20 added.
(3) Extension 2
ext
imm13
; imm13(3:0) = imm24(23:20)
ext
imm13
; = imm24(19:7)
ld.a
[%sp + imm7],%rs
; memory address = sp + imm24,
; imm7 = imm24(6:0)
The two ext instructions extend the displacement to a 24-bit quantity. As a result, the content
of the rs register is transferred to the address indicated by the content of the SP with the 24-bit
immediate imm24 added.
(4) Delayed slot instruction
This instruction may be executed as a delayed slot instruction by writing it directly after
a branch instruction with the “d” bit. In this case, extension of the immediate by the ext
instruction cannot be performed.
Example
ext
0x1
ld.a
[%sp + 0x2],%r0
; [sp + 0x82]
← r0
Caution
The SP and the displacement must specify a 32-bit boundary address (two least significant bits =
0). Specifying other address causes an address misaligned interrupt. Note, however, that the data
transfer is performed by setting the two least significant bits of the address to 0.