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brk.S revision 1.9.10.1 
      1 /*	$NetBSD: brk.S,v 1.9.10.1 2014/08/20 00:02:09 tls Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1990 The Regents of the University of California.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  *
     31  *	from: @(#)brk.s	5.2 (Berkeley) 12/17/90
     32  */
     33 
     34 #include "SYS.h"
     35 
     36 	.globl	_C_LABEL(_end)
     37 	.globl	_C_LABEL(__curbrk)
     38 
     39 #ifdef WEAK_ALIAS
     40 WEAK_ALIAS(brk, _brk)
     41 #endif
     42 
     43 	.data
     44 	.align	0
     45 	.globl	_C_LABEL(__minbrk)
     46 	.hidden	_C_LABEL(__minbrk)
     47 	.type	_C_LABEL(__minbrk),#object
     48 _C_LABEL(__minbrk):
     49 	.word	_C_LABEL(_end)
     50 
     51 /*
     52  * Change the data segment size
     53  */
     54 ENTRY(_brk)
     55 	ldr	r1, .Lminbrk
     56 #ifdef __PIC__
     57 	adr	r3, .Lminbrk
     58 	adds	r1, r1, r3
     59 #endif
     60 	/* Get the minimum allowable brk address */
     61 	ldr	r1, [r1]
     62 
     63 	/*
     64 	 * Valid the address specified and set to the minimum
     65 	 * if the address is below minbrk.
     66 	 */
     67 	cmp	r0, r1
     68 #ifdef __thumb__
     69 	bcs	1f
     70 	mov	r0, r1
     71 1:
     72 #else
     73 	movcc	r0, r1
     74 #endif
     75 	mov	r2, r0
     76 	SYSTRAP(break)
     77 	_INVOKE_CERROR()
     78 
     79 	ldr	r1, .Lcurbrk
     80 #ifdef __PIC__
     81 	adds	r1, r1, r3
     82 #endif
     83 	/* Store the new address in curbrk */
     84 	str	r2, [r1]
     85 
     86 	/* Return 0 for success */
     87 	movs	r0, #0
     88 	RET
     89 
     90 	.align	0
     91 .Lminbrk:
     92 	.word	REL_SYM(_C_LABEL(__minbrk), .Lminbrk)
     93 .Lcurbrk:
     94 	.word	REL_SYM(_C_LABEL(__curbrk), .Lminbrk)
     95 END(_brk)
     96