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BTST
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Testing a bit
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BTST
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Bit TeST
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[Syntax]
BTST src, src2
[Operation]
(1)When src2 is a memory location:
unsigned char src2;
Z = ~(( src2 >> ( src & 7 )) & 1 );
C = (( src2 >> ( src & 7 )) & 1 );
(2)When src2 is a register:
register unsigned long src2;
Z = ~(( src2 >> ( src & 31 )) & 1 );
C = (( src2 >> ( src & 31 )) & 1 );
[Function]
- | This instruction moves the inverse of the value of the bit of scr2, which is specified by src, to the Z flag and the value of the bit of scr2, which is specified by src, to the C flag. |
- | The immediate value given as src is the number (position) of the bit. |
- | The range for IMM:3 operands is 0 ? IMM:3 ? 7. The range for IMM:5 is 0 ? IMM:5 ? 31. |
[Instruction Format]
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(1)BTST src, src2
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#IMM:3
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[Rs2].B
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#IMM:3
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dsp:8[Rs2].B
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#IMM:3
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dsp:16[Rs2].B
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Rs
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[Rs2].B
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Rs
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dsp:8[Rs2].B
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Rs
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dsp16:[Rs2].B
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(2)BTST src, src2
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#IMM:5
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Rs2
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Rs
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Rs2
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[Flag Change]
Conditions
C : The flag is set if the specified bit is 1; otherwise it is cleared.
Z : The flag is set if the specified bit is 0; otherwise it is cleared.
[Description Example]
BTST #7, [R2]
BTST R1, [R2]
BTST #31, R2
BTST R1, R2