
BT
SC140 DSP Core Reference Manual A-109
BT Branch If True (AGU) BT
Description
Status and Conditions that Affect Instruction
Status and Conditions Changed by Instruction
None.
Example
BT lbl
Operation Assembler Syntax
If T==1, then PC + displacement → PC
BT <label
BT >label
BT <label
BT >label
Branches to label if the true bit is set. If the T bit is set, the program continues executing at location
PC + displacement. If the T bit is cleared, the PC is updated to point to the next execution set, and the
program continues executing sequentially. The displacement, calculated by the assembler and linker, is a
two’s complement integer that represents the relative distance from the current PC to the destination label.
The assembler determines if the PC relative displacement is a short branch (<label [–2
8
≤ displacement <
2
8
, W]) or a long branch (>label [–2
20
≤ displacement < –2
8
, W and 2
8
≤ displacement < 2
20
, W]).
Register Address Bit Name Description
SR[1] T True bit
Instruction Result
cmpeq.w #$35,d1 Equal, so T bit in SR set.
bt lbl move.w #$29,d1 Branch taken, move.w executed, d1=$29.
inc d1 Skipped over.
move.w #$47,d2 Skipped over.
- - - - Skipped over.
- - - - Skipped over.
- - - - Skipped over.
lbl move.w #$16,d4 Execution continues here at lbl, d4=$16.
Register/Memory Address Before BT After
SR
$00E4 0002
d1
$0035 $0029
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