BIT BIT TEST
|
Purpose |
test a set of bits for all zero |
|
Format |
opcode mask.rx, src.rx |
|
Operation |
tmp ß src AND mask; |
|
Condition codes |
N ß tmp LSS 0; Z ß tmp EQL 0; V ß 0; C ß C; |
|
Exceptions |
None |
|
Opcodes |
93 BITB Bit Test Byte B3 BITW Bit Test Word D3 BITL Bit Test Long |
|
Description |
The mask operand is ANDed with the source operand. Both operands are unaffected. The only action is to affect condition codes. |
|
Notes |
|
Example 1
The program displays message on the screen, which effected from the result of BITL command.
.text
main: .word 0
movl $0xFF, r2
movl $0xFF, r3
# first case - should be True
bitl r2, r3
bneq eq1
calls $0, prn_false
jmp next_stage
eq1: calls $0, prn_true
# second case - should be False
next_stage:
movl $0x0F, r2
movl $0xF0, r3
bitl r2, r3
bneq eq2
calls $0, prn_false
jmp end_prog
eq2: calls $0, prn_true
end_prog:
pushl $0
calls $1, .exit
prn_false: .word 0
pushal lbl_false
pushal format
calls $2, .printf
ret
prn_true: .word 0
pushal lbl_true
pushal format
calls $2, .printf
ret
.data
lbl_true: .asciz "True"
lbl_false: .asciz "False"
format: .asciz "%s\n"