Texas Instruments MSP50C6xx - Manual (Page 186)

Individual Instruction Descriptions
4-100
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 previous italic text on the bug in this instruction at the
present time.