4.176.1 setjmp.S

/* Copyright (c) 2002, Marek Michalkiewicz
   All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are met:

   * Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in
     the documentation and/or other materials provided with the
     distribution.
   * Neither the name of the copyright holders nor the names of
     contributors may be used to endorse or promote products derived
     from this software without specific prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  POSSIBILITY OF SUCH DAMAGE. */

/* $Id$ */



/*
   setjmp.S

   Contributors:
     Created by Marek Michalkiewicz <marekm@linux.org.pl>
 */

/*
   jmp_buf:
    offset  size    description
     0  16/2    call-saved registers (r2-r17)
                (AVR_TINY arch has only 2 call saved registers (r18,r19))
    16/2     2  frame pointer (r29:r28)
    18/4     2  stack pointer (SPH:SPL)
    20/6     1  status register (SREG)
    21/7     2/3    return address (PC) (2 bytes used for <=128Kw flash)
    23/24/9 = total size (AVR_TINY arch always has 2 bytes PC)
   All multibytes are stored as little-endian.

   int setjmp(jmp_buf __jmpb);
   void longjmp(jmp_buf __jmpb, int __val) __attribute__((noreturn));
 */

#ifndef __DOXYGEN__

#include <avr/io.h>
#include "macros.inc"

/* ???: What was a reason to use aliases for common registers?
   Check the address: is it a port number (value for IN/OUT)?   */
#if AVR_STACK_POINTER_LO_ADDR != 0x3D   \
     || AVR_STATUS_ADDR != 0x3F
# error  "Strange address of common registers SPL, SREG"
#endif

#define jmpb_hi r25
#define jmpb_lo r24
#define val_hi  r23
#define val_lo  r22

#define ret_lo  r24
#define ret_hi  r25

    ASSEMBLY_CLIB_SECTION

    .global _U(setjmp)
    .type   _U(setjmp), @function

_U(setjmp):
    X_movw  XL, jmpb_lo
  ; save call-saved registers and frame pointer
#if !defined(__AVR_TINY__)
    .irp    .L_regno, 2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,28,29
#else
    .irp    .L_regno, 18,19,28,29
#endif
    st  X+, r\.L_regno
    .endr
  ; get return address
#if  defined(__AVR_3_BYTE_PC__) && __AVR_3_BYTE_PC__
    pop __tmp_reg__     ; used below
#endif
    pop ZH
    pop ZL
  ; save stack pointer (after poping)
    in  ret_lo, AVR_STACK_POINTER_LO_ADDR
    st  X+, ret_lo
#ifdef _HAVE_AVR_STACK_POINTER_HI    
    in  ret_lo, AVR_STACK_POINTER_HI_ADDR
    st  X+, ret_lo
#else
    st  X+, __zero_reg__
#endif
  ; save status register (I flag)
    in  ret_lo, AVR_STATUS_ADDR
    st  X+, ret_lo
  ; save return address
    st  X+, ZL
    st  X+, ZH
  ; return zero
    clr ret_lo
    clr ret_hi
#if  defined(__AVR_3_BYTE_PC__) && __AVR_3_BYTE_PC__
    st  X+, __tmp_reg__
    rjmp    .L_jmp3
#else
    ijmp
#endif
    .size   _U(setjmp), . - _U(setjmp)

    .global _U(longjmp)
    .type   _U(longjmp), @function

_U(longjmp):
    X_movw  XL, jmpb_lo
  ; return value
    X_movw  ret_lo, val_lo
  ; if zero, change to 1
    cpi ret_lo, 1
    cpc ret_hi, __zero_reg__
    adc ret_lo, __zero_reg__
  ; restore call-saved registers and frame pointer
#if !defined(__AVR_TINY__)
    .irp    .L_regno, 2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,28,29
#else
    .irp    .L_regno, 18,19,28,29
#endif
    ld  r\.L_regno, X+
    .endr
  ; restore stack pointer (SP value before the setjmp() call) and SREG
    ld  ZL, X+
    ld  ZH, X+
    ld  __tmp_reg__, X+
#if  defined (__AVR_XMEGA__) && __AVR_XMEGA__
    /* A write to SPL will automatically disable interrupts for up to 4
       instructions or until the next I/O memory write. */
    out AVR_STATUS_ADDR, __tmp_reg__
    out AVR_STACK_POINTER_LO_ADDR, ZL
    out AVR_STACK_POINTER_HI_ADDR, ZH
#else
# ifdef _HAVE_AVR_STACK_POINTER_HI
    /* interrupts disabled for shortest possible time (3 cycles) */
    cli
    out AVR_STACK_POINTER_HI_ADDR, ZH
# endif
    /* Restore status register (including the interrupt enable flag).
       Interrupts are re-enabled only after the next instruction.  */
    out AVR_STATUS_ADDR, __tmp_reg__
    out AVR_STACK_POINTER_LO_ADDR, ZL
#endif
  ; get return address and jump
    ld  ZL, X+
    ld  ZH, X+
#if  defined(__AVR_3_BYTE_PC__) && __AVR_3_BYTE_PC__
    ld  __tmp_reg__, X+
.L_jmp3:
    push    ZL
    push    ZH
    push    __tmp_reg__
    ret
#else
    ijmp
#endif
    .size   _U(longjmp), . - _U(longjmp)

#endif  /* !__DOXYGEN__ */