User manual

Instruction Set
3-49
RISC 16−Bit CPU
JN Jump if negative
Syntax JN label
Operation if N = 1: PC + 2 × offset −> PC
if N = 0: execute following instruction
Description The negative bit (N) of the status register is tested. If it is set, the 10-bit signed
offset contained in the instruction LSBs is added to the program counter. If N
is reset, the next instruction following the jump is executed.
Status Bits Status bits are not affected.
Example The result of a computation in R5 is to be subtracted from COUNT. If the result
is negative, COUNT is to be cleared and the program continues execution in
another path.
SUB R5,COUNT ; COUNT − R5 −> COUNT
JN L$1 ; If negative continue with COUNT=0 at PC=L$1
...... ; Continue with COUNT≥0
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L$1 CLR COUNT
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