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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.