SX Users Manual Rev. 3.1
80
© 2000 Scenix Semiconductor, Inc. All rights reserved.
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Chapter 3 Instruction Set
3.6.12 DEC fr
Decrement fr
Operation:
fr = fr -1
Bits affected:
Z
Opcode:
0000 111f ffff
Description:
This instruction decrements the specified register file by one.
If the file register contains 01h, it is decremented to 00h and the Z bit is set.
Otherwise, the bit is cleared.
If the file register contains 00h, it is decremented to FFh.
Cycles:
1
Example:
dec
$18
This example decrements file register 18h.