Freescale Semiconductor StarCore SC140 - Manual (Page 419)

BSR
SC140 DSP Core Reference Manual A-105
BSR
Branch to Subroutine (AGU)
BSR
Description
Status and Conditions that Affect Instruction
Status and Conditions Changed by Instruction
None.
Example
bsr _label
Operation Assembler Syntax
(Next PC)
→ (SP); SR → (SP + 4); SP + 8 → SP;
PC + displacement
→ PC; (Next PC)→ RAS
BSR BSR >label
BSR
BSR >label
Pushes the next PC and SR onto the stack and causes program execution to continue at location PC +
displacement. 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 (
8
≤ displacement < 2
8 , W]) or a long branch
(
>label [–2
20
≤ displacement < –2
8 , W and 2 8
≤ displacement < 2
20 , W]). In addition to being pushed onto
the stack, the next PC is stored in the return address from subroutine register (RAS) and RAS becomes
valid.
Register Address Bit Name Description
SR[18] EXP Determines the stack pointer used in instructions that have a stack
pointer as an operand.
Register/Memory Address Before After
SR $00E0 0000
_label (displacement) $0000 0014
PC $0000 0002 $0000 0016
NSP $30 $38
($30) $0000 0006
($34) $00E0 0000