ZiLOG eZ8, User Manual

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UM012811-0904 Architectural Overview
eZ8 CPU
User Manual
7
Arithmetic Logic Unit
The Arithmetic Logic Unit (ALU) performs arithmetic and logical operations on the data.
The arithmetic operations include addition, subtraction, and multiplication. The logical
functions include binary logic operations, bit shifting, and bit rotation.
Byte Ordering
For multi-byte data, the eZ8 CPU stores the most significant byte in the lowest memory
address. For example, the value 1 can be stored as a 2-byte (16-bit) number in Register
Table 2. Condition Codes
Binary Hex
Assembly
Mnemonic
Definition Flag Test Operation
0000 0 F Always False –
0001 1 LT Less Than (S XOR V) = 1
0010 2 LE Less Than or Equal (Z OR (S XOR V)) = 1
0011 3 ULE Unsigned Less Than or Equal (C OR Z) = 1
0100 4 OV Overflow V = 1
0101 5 Ml Minus S = 1
0110 6 Z Zero Z = 1
0110 6 EQ Equal Z = 1
0111 7 C Carry C = 1
0111 7 ULT Unsigned Less Than C = 1
1000 8 T (or blank) Always True –
1001 9 GE Greater Than or Equal (S XOR V) = 0
1010 A GT Greater Than (Z OR (S XOR V)) = 0
1011 B UGT Unsigned Greater Than (C = 0 AND Z = 0)
1100 C NOV No Overflow V = 0
1101 D PL Plus S = 0
1110 E NZ Non-Zero Z = 0
1110 E NE Not Equal Z = 0
1111 F NC No Carry C = 0
1111 F UGE Unsigned Greater Than or Equal C = 0