DP8344 datasheet(141/184 Pages) NSC

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60 Reference Section (Continued)

JMP

Conditional Relative Jump

Jcc

Syntax

JMP

f s n

immediate

Jcc

immediate (optional syntax)

Affected Flags

None

Description

Conditionally transfers control to the instruction at the mem-

ory address calculated by adding the contents of the Pro-

gram Counter to the immediate value n (sign extended to

16 bits) if the state of the flag referenced by f is equal to the

state of the bit s or optionally if the condition cc is met

See the tables below for the flags that f can reference and

the conditions that cc may specify Since the immediate val-

ue n is an 8-bit two’s complement displacement the condi-

tional relative jump’s range is from a127 to b128 relative

to the Program Counter Note that the Program Counter ini-

tially contains the memory address of the next instruction

following the jump

Example

This example demonstrates both syntaxes of the condition-

al relative jump instruction testing for a non-zero result from

a previous instruction (ie

Z e0) If the condition is

met then control transfers to the instruction labeled

‘‘Loopback’’ else the next instruction following the jump is

executed

JMP

000B0Loopback

jump on not zero

JNZ

Loopback

jump on not zero

Condition Specification Table for ‘‘cc’’

Meaning

Condition Tested for

Zero

Not Zero

Equal

NEQ

Not Equal

Carry

No Carry

Overflow

No Overflow

Negative

Positive

Receiver Active

NRA

Not Receiver Active

Receiver Error

NRE

No Receiver Error

Data Available

DAV

NDA

No Data Available

DAV

TFF

Transmitter FIFO Full

TFF

NTFF

Transmitter FIFO Not Full

TFF

Instruction Format

1101

Opcode

T-states

2 if condition is not met

3 if condition is met

Bus Timing

Figure 6-1 if condition is not met

Figure 6-2 if condition is met

Operation

JMP

f s n

If flag f is in state s

then PC a n(sign extended)

xPC

Jcc

If cc condition is true

then PC a n(sign extended)

xPC

Flag Reference Table for ‘‘f’’

(binary)

Flag Reference

(000)

in CCR

(001)

in CCR

(010)

in CCR

(011)

in CCR

(100)

in TSR

(101)

in TSR

(110)

DAV in TSR

(111)

TFF

in TSR

Note

The value of f for DAV differs from the numeric

value for the position of DAV in TSR

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