Freescale Semiconductor StarCore SC140 - Manual (Page 527)

JSR
SC140 DSP Core Reference Manual A-213
JSR
Jump to Subroutine (AGU)
JSR
Description
These operations jump to the subroutine location in program memory that is given by the instruction’s
effective address. The operation includes an implicit push of the status register (SR) and the program
counter (PC) onto the stack. The value of PC stored on the stack is that of the execution set following the
current execution set. In addition, the value of the next PC is stored in the RAS shadow register. The
destination address cannot be in the middle of an execution set.
Status and Conditions that Affect Instruction
Status and Conditions Changed by Instruction
None.
Example
jsr r6
Operation Assembler Syntax
(Next PC)
→ (SP); SR → (SP + 4); SP + 8 → SP; label → PC
JSR label {0
≤ label < 2
32 ,W}
(Next PC)
→ (SP); SR → (SP + 4); SP + 8 → SP; Rn → PC
JSR Rn
JSR label
Jumps to a memory location specified by the label. The assembler and linker calculate the 32-bit absolute
destination address from the label.
JSR Rn
Jumps to a memory location contained in an address register (Rn). The value in Rn must be word-aligned.
Register Address Bit Name Description
SR[18] EXP Determines which stack pointer is used.
Register/Memory Address Before After
R6 $0000 0012
PC $0000 0004 $0000 0012
SP $0000 0100 $00000108
SR $00E0 0000
($00000100) $0000 000A
($00000104) $00E0 0000