CHecK bounds
NAME
CHK -- Check bounds
SYNOPSIS
CHK <ea>,Dn
Size = (Word)
Size = (Word, Long) (68020+)
FUNCTION
Compares the value in the data register specified to zero and to the
upper bound. The upper bound is a twos complement integer. If the
register value is less than zero or greater than the upper bound,
a CHK instruction, vector number 6, occurs.
FORMAT
-----------------------------------------------------------------
|15 |14 |13 |12 |11 |10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|-----------|-------|---|-----------|-----------|
| 0 | 1 | 0 | 0 | REGISTER | SIZE | 0 | MODE | REGISTER |
----------------------------------------=========================
<ea>
REGISTER
<ea> specifies upper bound, 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) |111 | 010 |
|-------------------------------| |-----------------------------|
| (An)+ |011 |N° reg. An| | (d8,PC,Xi) |111 | 011 |
|-------------------------------| |-----------------------------|
| -(An) |100 |N° reg. An| | (bd,PC,Xi) |111 | 011 |
|-------------------------------| |-----------------------------|
| (d16,An) |101 |N° reg. An| |([bd,PC,Xi],od)|111 | 011 |
|-------------------------------| |-----------------------------|
| (d8,An,Xi) |110 |N° reg. An| |([bd,PC],Xi,od)|111 | 011 |
|-------------------------------| |-----------------------------|
| (bd,An,Xi) |110 |N° reg. An| | #data |111 | 100 |
|-------------------------------| -------------------------------
|([bd,An,Xi]od) |110 |N° reg. An|
|-------------------------------|
|([bd,An],Xi,od)|110 |N° reg. An|
---------------------------------
SIZE
11->one Word operation
10->one Long operation
RESULT
X - Not affected
N - Set if Dn < 0; cleared if Dn > <ea>. Undefined otherwise.
Z - Undefined.
V - Undefined.
C - Undefined.
SEE ALSO
CMP CMPI CMPA
CHK2
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& witbrock@cs.cmu.edu