Z8F640x/Z8F480x/Z8F320x/Z8F240x/Z8F160x
Z8 Encore!®
186
Condition Codes
The C, Z, S and V flags control the operation of the conditional jump (JP cc and JR cc)
instructions. Sixteen frequently useful functions of the flag settings are encoded in a 4-bit
field called the condition code (cc), which forms Bits 7:4 of the conditional jump instruc-
tions. The condition codes are summarized in Table 117. Some binary condition codes can
be created using more than one assembly code mnemonic. The result of the flag test oper-
ation is used to decide if the conditional jump is executed.
Table 117. Condition Codes
Assembly
Binary
0000
0001
0010
0011
0100
0101
0110
0110
0111
0111
1000
1001
1010
1011
1100
1101
1110
1110
1111
1111
Hex
Mnemonic Definition
Flag Test Operation
0
F
LT
Always False
Less Than
–
1
(S XOR V) = 1
2
LE
ULE
OV
Ml
Z
Less Than or Equal
Unsigned Less Than or Equal
Overflow
(Z OR (S XOR V)) = 1
3
(C OR Z) = 1
4
V = 1
5
Minus
S = 1
6
Zero
Z = 1
6
EQ
C
Equal
Z = 1
7
Carry
C = 1
7
ULT
Unsigned Less Than
C = 1
8
T (or blank) Always True
–
9
GE
GT
Greater Than or Equal
(S XOR V) = 0
A
B
C
D
E
E
F
F
Greater Than
Unsigned Greater Than
No Overflow
Plus
(Z OR (S XOR V)) = 0
UGT
NOV
PL
(C = 0 AND Z = 0) = 1
V = 0
S = 0
Z = 0
Z = 0
C = 0
NZ
Non-Zero
NE
Not Equal
NC
No Carry
UGE
Unsigned Greater Than or Equal C = 0
PS017610-0404
eZ8 CPU Instruction Set
ZILOG [ ZILOG, INC. ]
