NEGate with eXtend
NAME
NEGX -- Negate with extend
SYNOPSIS
NEGX <ea>
Size = (Byte, Word, Long)
FUNCTION
Perform an operation similar to a NEG, with the
exception that the operand and the extend bit are both
subtracted from zero. The result then is being placed in
the given <ea>.
As with ADDX, SUBX, ABCD,
SBCD, and NBCD, it can be useful to set
the zero flag before performing this operation so that
multi precision operations can be tested for zero.
FORMAT
-----------------------------------------------------------------
|15 |14 |13 |12 |11 |10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|-------|-----------|-----------|
| 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | SIZE | MODE | REGISTER |
----------------------------------------=========================
<ea>
SIZE
00->Byte.
01->Word.
10->Long.
REGISTER
<ea> specifies destination operand, addressing modes allowed are:
--------------------------------- -------------------------------
|Addressing Mode|Mode| Register | |Addressing Mode|Mode|Register|
|-------------------------------| |-----------------------------|
| Dn |000 |N° reg. Dn| | Abs.W |111 | 000 |
|-------------------------------| |-----------------------------|
| An | - | - | | Abs.L |111 | 001 |
|-------------------------------| |-----------------------------|
| (An) |010 |N° reg. An| | (d16,PC) | - | - |
|-------------------------------| |-----------------------------|
| (An)+ |011 |N° reg. An| | (d8,PC,Xi) | - | - |
|-------------------------------| |-----------------------------|
| -(An) |100 |N° reg. An| | (bd,PC,Xi) | - | - |
|-------------------------------| |-----------------------------|
| (d16,An) |101 |N° reg. An| |([bd,PC,Xi],od)| - | - |
|-------------------------------| |-----------------------------|
| (d8,An,Xi) |110 |N° reg. An| |([bd,PC],Xi,od)| - | - |
|-------------------------------| |-----------------------------|
| (bd,An,Xi) |110 |N° reg. An| | #data | - | - |
|-------------------------------| -------------------------------
|([bd,An,Xi]od) |110 |N° reg. An|
|-------------------------------|
|([bd,An],Xi,od)|110 |N° reg. An|
---------------------------------
RESULT
X - Set the same as the carry bit.
N - Set if the result is negative, otherwise cleared.
Z - Cleared if the result is non-zero, otherwise unchanged.
V - Set if an overflow is generated, cleared otherwise.
C - Set if a borrow is generated, otherwise cleared.
SEE ALSO
NEG NBCD ADDX SUBX
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& witbrock@cs.cmu.edu