ZiLOG Z80380 User Manual page 37

Z
ILOG
5.2.7 Condition Codes
The Carry, Zero, Sign, and Parity/Overflow flags are used
to control the operation of the conditional instructions. The
operation of these instructions is a function of the state of
one of the flags. Special mnemonics called condition
codes are used to specify the flag setting to be tested
during execution of a conditional instruction; the condition
codes are encoded into a 3-bit field in the instruction
opcode itself.
Condition Codes for Jump, Call, and Return Instructions
Mnemonic Meaning
NZ Not Zero*
Z Zero*
NC No Carry*
C Carry*
NV No Overflow
PO Parity Odd
V Overflow
PE Parity Even
NS No Sign
P Plus
S Sign
M Minus
*Abbreviated set
Condition Codes for Jump Relative and Call Relative Instructions
Mnemonic Meaning
NZ Not Zero
Z Zero
NC No Carry
C Carry
DC-8297-03
Table 5-1 lists the condition code mnemonic, the flag
setting it represents, and the binary encoding for each
condition code.
Table 5-1. Condition codes
Flag Setting
Z = 0
Z = 1
C = 0
C = 1
V = 0
V = 0
V = 1
V = 1
S = 0
S = 0
S = 1
S = 1
Flag Setting
Z = 0
Z = 1
C = 0
C = 1
Binary Code
000
001
010
011
100
100
101
101
110
110
111
111
Binary Code
100
101
110
111
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U ' M
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