Excalibur electronic A-MNL-NIOSPROG-01.1 用户手册
Altera Corporation
57
32323232
32-Bit Instruction Set
2
3
2
-B
it In
st
st
ru
ctio
n
n
Se
t
t
IFS
Conditionally Execute Next Instruction
Operation:
if (condition IMM4 is false)
then begin
then begin
if (Mem16[PC + 2] is PFX)
then PC
then PC
← PC + 6
else PC
← PC + 4
end
Assembler Syntax:
IFS cc_IMM4
Example:
IFS cc_ne
BSR SendIt ; only call if Z flag set
NOP ; (delay slot) executed in either case
Description:
Execute next instruction if specified condition is true, skip if condition is false. If
the next instruction is PFX, then both PFX and the instruction following PFX are
the next instruction is PFX, then both PFX and the instruction following PFX are
skipped together.
Condition Codes:
Settings:
1
These condition
codes have
different numeric
values for IFS and
SKPS instructions.
codes have
different numeric
values for IFS and
SKPS instructions.
cc_nc
0x0
(not C)
cc_c
0x1
(C)
cc_nz
0x2
(not Z)
cc_z
0x3
(Z)
cc_pl
0x4
(not N)
cc_mi
0x5
(N)
cc_lt
0x6
(N xor V)
cc_ge
0x7
(not (N xor V))
cc_gt
0x8
(Not (Z or (N xor V)))
cc_le
0x9
(Z or (N xorV))
cc_nv
0xa
(not V)
cc_v
0xb
(V)
cc_hi
0xc
(not (C or Z))
cc_la
0xd
(C or Z)
Additional alias flags allowed:
cc_cs = cc_c
cc_eq = cc_z
cc_n = cc_mi
cc_vs = cc_v
cc_cc = cc_nc
cc_ne = cc_nz
cc_vc = cc_nv
cc_p = cc_pl
Codes mean execute if, e.g., ifs cc_eq means execute if equal
Instruction Format:
i4w
Instruction Fields:
IMM4 = 4-bit immediate value
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0
1
1
1
1
1
1
0
1
1
1
0
IMM4