Datasheet

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Instruction Set Description

4.6.4.9 RETA

* RETA Return from subroutine

RETA

Syntax

Operation @SP → PC.15:0 LSBs (15:0) of saved PC to PC.15:0

SP + 2 → SP

@SP → PC.19:16 MSBs (19:16) of saved PC to PC.19:16

SP + 2 → SP

MOVA @SP+,PC

Emulation

Description The 20-bit return address information, pushed onto the stack by a CALLA instruction, is

restored to the PC. The program continues at the address following the subroutine call.

The SR bits SR.11:0 are not affected. This allows the transfer of information with these

bits.

Status Bits N: Not affected

Z: Not affected

C: Not affected

V: Not affected

Mode Bits OSCOFF, CPUOFF, and GIE are not affected.

Example Call a subroutine SUBR from anywhere in the 20-bit address space and return to the

address after the CALLA

CALLA #SUBR ; Call subroutine starting at SUBR

... ; Return by RETA to here

SUBR PUSHM.A #2,R14 ; Save R14 and R13 (20 bit data)

... ; Subroutine code

POPM.A #2,R14 ; Restore R13 and R14 (20 bit data)

RETA ; Return (to full address space)

269

SLAU144J–December 2004–Revised July 2013 CPUX

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