the two instructions
AHI 1,-1
AHI 1,X'FFFF'
-
if they are compiled produce coding
00000000 90EC D00C 0000000C 5 STM 14,12,12
(13)
00000004 A71A FFFF FFFFFFFF 6 AHI 1,-1
00000008 A71A FFFF 0000FFFF 7 AHI 1,X'FFFF'
the development in the compilation of any immediate operand depends on the
type of instruction in which it is used and how it is interpreted by the
instruction itself.
with reference to: principle of operation v2r2:
for example considering the move immediate instructions we have:
For MOVE (MVC), each operand is processed left to right. When the operands
overlap, the result is obtained as if the operands were processed one byte
at a time and each result byte were stored immediately after fetching the
necessary operand byte.
For MOVE (MVI, MVIY), the first operand is one byte in length, and only one
byte is stored.
For MOVE (MVGHI, MVHHI, and MVHI,), the second operand is treated as a
16-bit signed integer, signextended as necessary,
and placed in the first-operand location.
The first operand is two, four, or eight bytes for MVHHI, MVHI, and MVGHI,
respectively.
Aldo Crosio
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riservate ed a uso esclusivo dei destinatari. Qualora Le fosse pervenuto per
errore, La invitiamo ad eliminarlo immediatamente, dandocene gentilmente
comunicazione. Grazie.
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