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Texas Instruments MSP50C614 User Manual

Page 191

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Individual Instruction Descriptions

4-99

Assembly Language Instructions

MOV AP1, 3

; Point to loc corresponding to

; extended word in acc

MOVS A0, *R0

; R0 POINTS TO VALUE IN MEMORY

EXTSGN A1

; not string version as above

Alternatively, the following code can do the same thing but requires more code:

MOV AP0, 0

; POINT TO LSW OF ACCUM STRING

MOV AP1, 3

; Point to loc corresponding to

; extended word in acc

ZAC A1

; INITIALIZE EXTENDED SIGN VALUE as positive

MOVS A0, *R0 ; R0 POINTS TO VALUE IN MEMORY

JNS POSITIVE ; branch around negative extension,

; accepting default pos extension

NOT A1

; INVERT EXTENDED SIGN WORD FOR NEG CASE POSITIVE

......

See Also

EXTSGN

Example 4.14.17.1

EXTSGNS A0~

Sign extend accumulator string A0~. See the above IMPORTANT note on the bug in this instruction at
the present time.