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7 DETAILS OF INSTRUCTIONS
7-4
EPSON
S1C17 FAMILY S1C17 CORE MANUAL
add
%rd, %rs
add/c
%rd, %rs
add/nc %rd, %rs
Function
16-bit addition
Standard)
rd
(15:0)
← rd(15:0) + rs(15:0), rd(23:16) ← 0
Extension 1) rd(15:0)
← rs(15:0) + imm13(zero extended), rd(23:16) ← 0
Extension 2) rd(15:0)
← rs(15:0) + imm16, rd(23:16) ← 0
Code
15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
0 0 1 1 1 0
r d
1 0 0 0
r s
add
|
0 0 1 1 1 0
r d
0 0 0 0
r s
add/c
|
0 0 1 1 1 0
r d
0 1 0 0
r s
add/nc
|
Flag
IL IE
C
V
Z
N
– –
add
|
– – –
add/c, add/nc
|
Mode
Src:Register direct %rs = %r0 to %r7
Dst:Register direct %rd = %r0 to %r7
CLK
One cycle
Description (1) Standard
add
%rd,%rs
; rd
← rd + rs
The content of the rs register is added to the rd register. The operation is performed in 16-bit
size, and bits 23–16 of the rd register are set to 0.
(2) Extension 1
ext
imm13
add
%rd,%rs
; rd
← rs + imm13
The 13-bit immediate imm13 is added to the content of the rs register after being zero-extended,
and the result is loaded into the rd register. The operation is performed in 16-bit size, and bits
23–16 of the rd register are set to 0. The content of the rs register is not altered.
(3) Extension 2
ext
imm13
; imm13(2:0) = imm16(15:13)
ext
imm13
; = imm16(12:0)
add
%rd,%rs
; rd
← rs + imm16
The 16-bit immediate imm16 is added to the content of the rs register, and the result is loaded
into the rd register. The operation is performed in 16-bit size, and bits 23–16 of the rd register
are set to 0. The content of the rs register is not altered.
(4) Conditional execution
The /c or /nc suffix on the opcode specifies conditional execution.
add/c
Executed as add when the C flag is 1 or executed as nop when the flag is 0
add/nc Executed as add when the C flag is 0 or executed as nop when the flag is 1
In this case, the ext instruction can be used to extend the operand.
(5) 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
(1) add
%r0,%r0
; r0 = r0 + r0
(2) ext
0x1
ext
0x1fff
add
%r1,%r2
; r1 = r2 + 0x3fff