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/*

    Copyright (c) 1993 Open Software Foundation, Inc.

    All Rights Reserved

    Permission to use, copy, modify, and distribute this software

    and its documentation for any purpose and without fee is hereby

    granted, provided that the above copyright notice appears in all

    copies and that both the copyright notice and this permission

    notice appear in supporting documentation.

    OSF DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING

    ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A

    PARTICULAR PURPOSE.

    IN NO EVENT SHALL OSF BE LIABLE FOR ANY SPECIAL, INDIRECT, OR

    CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM

    LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,

    NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION

    WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

*/

/*

    		 Crown Copyright (c) 1997

    This TenDRA(r) Computer Program is subject to Copyright

    owned by the United Kingdom Secretary of State for Defence

    acting through the Defence Evaluation and Research Agency

    (DERA).  It is made available to Recipients with a

    royalty-free licence for its use, reproduction, transfer

    to other parties and amendment for any purpose not excluding

    product development provided that any such use et cetera

    shall be deemed to be acceptance of the following conditions:-

        (1) Its Recipients shall ensure that this Notice is

        reproduced upon any copies or amended versions of it;

        (2) Any amended version of it shall be clearly marked to

        show both the nature of and the organisation responsible

        for the relevant amendment or amendments;

        (3) Its onward transfer from a recipient to another

        party shall be deemed to be that party's acceptance of

        these conditions;

        (4) DERA gives no warranty or assurance as to its

        quality or suitability for any purpose and DERA accepts

        no liability whatsoever in relation to any use to which

        it may be put.

*/

/**********************************************************************

$Author: release $

$Date: 1998/02/04 15:48:47 $

$Revision: 1.2 $

$Log: getregs.c,v $

 * Revision 1.2  1998/02/04  15:48:47  release

 * Added OSF copyright message.

 *

 * Revision 1.1.1.1  1998/01/17  15:55:56  release

 * First version to be checked into rolling release.

 *

 * Revision 1.2  1996/10/04  16:01:04  pwe

 * add banners and mod for PWE ownership

 *

**********************************************************************/

/******************************************************************

		getregs.c

	Routines for choosing temporary registers. The next free

register is chosen cyclically from available t regs.

	The parameter is usually taken from a value of type space

(which has bits for fixed and floating regs).  A clear bit indicates

that the corresponding register is free for use.

******************************************************************/

#include "config.h"

#include "memtdf.h"

#include "codegen.h"

#include "myassert.h"

#include "comment.h"

#include "getregs.h"

/* next fixed reg to be allocated */

static int currentfix;

static long choosefix;

/* next float reg to be allocated */

static int currentfloat;

static long choosefloat;

/* reset getreg() and getfreg() back to start of sequence for proc 'tg' */

void settempregs PROTO_N ((tg)) PROTO_T (exp tg)

{

  currentfix = R_LAST_PARAM+1;/* R_11 it must be for parameters*/

  choosefix = RMASK(currentfix);

  currentfloat = FR_1;

  choosefloat = RMASK(currentfloat);

}

/* count how many free regs there are */

int freeregs PROTO_N ((rmask)) PROTO_T (long rmask)

{

  /* Free reg marked by 0 bit, count them */

  unsigned long bit = 1;

  int n = 0;

  while (bit != 0)

  {

    if ((rmask & bit) == 0)

      n++;

    bit <<= 1;

  }

  return n;

}

/* get a free temporary fixed pt reg */

int getreg PROTO_N ((fixed)) PROTO_T (long fixed)

{

  /*

   * Choose reg from set 'fixed'. Chosen in a cyclic order, to give good

   * chance for peep-hole optimiser finding something useful lying around. Bit

   * set in set 'fixed' means it is unavailable, we search for 0 bit.

   */

  int reg = -1;

  long start = choosefix;

  FULLCOMMENT3("getreg: from %#x, choosefix=%#x currentfix=%d", fixed, choosefix, currentfix);

  /* currentfix and choosefix are in step, one the reg number, one the mask */

  ASSERT(choosefix == RMASK(currentfix));

  for (;;)

  {

    if ((choosefix & fixed) == 0)

      reg = currentfix;

    ASSERT(reg != R_0);		/* R_0 not a fully functional reg, should never be in set */

    ASSERT(!IS_R_TMP(reg));	/* +++ R_TMP currently used as ad-hoc temp in

				 * various places */

    if (currentfix == R_LAST)

    {

      /* back to start */

      currentfix = R_FIRST;

      choosefix = RMASK(R_FIRST);

    }

    else

    {

      /* next reg */

      currentfix++;

      choosefix = choosefix << 1;

    }

    if (reg != -1)

    {

      FULLCOMMENT1("getreg: allocating %d", reg);

      ASSERT(IS_TREG(reg));

      return reg;

    }

    if (choosefix == start)

    {

      fail("getreg: too many regs required");

      return R_0;

    }

  }

}

/* get a free temporary floating reg */

int getfreg PROTO_N ((fl)) PROTO_T (long fl)

{

  /*

   * Choose reg from set 'fl'. Chosen in a cyclic order, to give good chance

   * for peep-hole optimiser finding something useful lying around. Bit set in

   * set 'float' means it is unavailable, we search for 0 bit.

   */

  int reg = -1;

  long start = choosefloat;

  FULLCOMMENT3("getfreg: from %#x, choosefloat=%#x currentfloat=%d", fl, choosefloat, currentfloat);

  /*

   * currentfloat and choosefloat are in step, one the reg number, one the

   * mask

   */

  ASSERT(choosefloat == RMASK(currentfloat));

  for (;;)

  {

    if ((choosefloat & fl) == 0)

      reg = currentfloat;

    if (currentfloat == R_FLT_LAST)

    {

      /* back to start */

      currentfloat = R_FLT_FIRST;

      choosefloat = RMASK(R_FLT_FIRST);

    }

    else

    {

      /* next reg */

      currentfloat++;

      choosefloat = choosefloat << 1;

    }

    if (reg != -1)

    {

      FULLCOMMENT1("getfreg: allocating %d", reg);

      ASSERT(IS_FLT_TREG(reg));

      return reg;

    }

    if (choosefloat == start)

    {

      fail("getfreg: too many float regs required");

      return 0;

    }

  }

}

/* return next branch unit cr reg to use */

int next_creg PROTO_Z ()

{

  /*

   * Cycle around cr 0,1,6,7.	+++ allocate as regs

   * cr3 & cr4 would require proc to save them.

   * cr4 & cr5 reserved for system use.

   */

  static int creg = 7;

  creg++;

  if (creg == 8)

    creg = 0;

  else if (creg == 2)

    creg = 6;

  return creg;

}