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7 DETAILS OF INSTRUCTIONS
S1C17 FAMILY S1C17 CORE MANUAL
EPSON
7-65
ld.a %rd, [%sp + imm7]
Function
32-bit data transfer
Standard)
rd
(23:0)
← A[sp + imm7](23:0), ignored ← A[sp + imm7](31:24)
Extension 1) rd(23:0)
← A[sp + imm20](23:0), ignored ← A[sp + imm20](31:24)
Extension 2) rd(23:0)
← A[sp + imm24](23:0), ignored ← A[sp + imm24](31:24)
Code
15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
1 1 1 0 1 1
r d
imm7
|
Flag
IL IE
C
V
Z
N
– – – – – –
|
Mode
Src:Register indirect with displacement
Dst:Register direct %rd = %r0 to %r7
CLK
Two cycles
Description (1) Standard
ld.a
%rd,[%sp + imm7]
; memory address = sp + imm7
The 32-bit data (the eight high-order bits are ignored) in the specified memory location is
transferred to the rd register. The content of the current SP with the 7-bit immediate imm7
added as displacement comprises the memory address to be accessed.
(2) Extension 1
ext
imm13
; = imm20(19:7)
ld.a
%rd,[%sp + imm7]
; 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
SP with the 20-bit immediate imm20 added comprises the memory address, the 32-bit data (the
eight high-order bits are ignored) in which is transferred to the rd register.
(3) Extension 2
ext
imm13
; imm13(3:0) = imm24(23:20)
ext
imm13
; = imm24(19:7)
ld.a
%rd,[%sp + imm7]
; 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 SP with the 24-bit immediate imm24 added comprises the memory address, the 32-bit
data (the eight high-order bits are ignored) in which is transferred to the rd register.
(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
%r0,[%sp + 0x2]
; r0
← [sp + 0x82]
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.