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3.7.2.2
Condition Code (AC.cc)
The processor sets the AC register's condition code flags (bits 0-2) to indicate the results of certain
instructions, such as compare instructions. Other instructions, such as conditional branch instruc-
tions, examine these flags and perform functions as dictated by the state of the condition code
flags. Once the processor sets the condition code flags, the flags remain unchanged until another
instruction executes that modifies the field.
Condition code flags show true/false conditions, inequalities (greater than, equal or less than
conditions) or carry and overflow conditions for the extended arithmetic instructions. To show true
or false conditions, the processor sets the flags as shown in
inequalities, the processor sets the condition code flags as shown in
Table 3-8. Condition Codes for True or False Conditions
Condition Code
010
2
000
2
Table 3-9. Condition Codes for Equality and Inequality Conditions
Condition Code
000
2
001
2
010
2
100
2
The term unordered is used when comparing floating point numbers. The i960 Jx processor does
not implement on-chip floating point processing.
To show carry out and overflow, the processor sets the condition code flags as shown in
Table
3-10.
Table 3-10. Condition Codes for Carry Out and Overflow
Condition Code
01X
2
0X1
2
PROGRAMMING ENVIRONMENT
Table
3-8. To show equality and
Table
3-9.
Condition
true
false
Condition
unordered
greater than
equal
less than
Condition
carry out
overflow
3
3-19
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