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minor thumb-mode fixes

/*
  ARM icache flush support using Linux syscall.  

  Copyright (C) 2000,2008 Free Software Foundation, Inc.

  This file is part of Gforth.

  Gforth is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License
  as published by the Free Software Foundation; either version 2
  of the License, or (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
*/
#include <stddef.h>

void cacheflush(void *p, size_t size) 
{
   /* For details, please see the Linux sources, files
    * arch/arm/kernel/traps.c, arch/arm/kernel/entry-common.S and
    * asm-arm/unistd.h
    * 
    * This syscall is supported by all 2.4 and 2.6 Linux kernels.  2.2 linux
    * kernels got first support with version 2.2.18.
    */

   asm("mov r0, %0\n"
       "mov r1, %1\n"
       "mov r2, #0\n"
#    if defined (__thumb__)
       /* Thumb syscall, either EABI or OABI, syscall number is passed in
	* 'r7'.  Note that Thumb EABI and OABI are generally not the same.  It
	* just happens that the simple cacheflush syscall doesn't expose any
	* of differences in calling conventions. */
       "mov r7, #0xf\n\t"	/* Thumb mode only allows 8-bit constants */
       "lsl r7, #16\n\t"
       "add r7, #0x2\n\t"
       "swi #0\n\t"      
#    elif defined (__ARM_EABI__)
       /* EABI non-Thumb syscall: syscall number passed in 'r7' (syscall base
	* number is 0x0).
        */
       "mov r7, #0xf0000\n\t"	/* only shifted 8-bit constants allowed */
       "orr r7, r7, #0x00002\n\t"	
       "swi #0\n\t"      
#    else
       /* OABI non-Thumb syscall: syscall number passed as part of 'swi'
	* instruction, base number is 0x900000 */
       "swi #0x9f0002\n"
#    endif
       :: "r"(p), "r"((long)p+size) :
       "r0", "r1", "r2", "r7");
}