/* -*- c -*- */
/*
 * Copyright 2007 Free Software Foundation, Inc.
 * 
 * This file is part of GNU Radio
 * 
 * GNU Radio 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 3, or (at your option)
 * any later version.
 * 
 * GNU Radio 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <gcell/gc_jd_stack.h>
#include <gcell/memory_barrier.h>

/*
 * begin extract from ppu_intrinics.h
 * FIXME handle this a different way
 */

#if !defined(__PPU__) && !defined(__ppc__) && !defined(__ppc64__)
    && !defined(__GNUC__)
  #error ppu_intrinsics.h included on wrong platform/compiler
#endif

#define __lwarx(base) __extension__		\
  ({unsigned int result;	       		\
    typedef  struct {char a[4];} wordsize;	\
    wordsize *ptrp = (wordsize*)(base);		\
  __asm__ volatile ("lwarx %0,%y1"		\
	   : "=r" (result)			\
	   : "Z" (*ptrp));			\
  result; })

#ifdef __powerpc64__
#define __ldarx(base) __extension__			\
  ({unsigned long long result;	       			\
    typedef  struct {char a[8];} doublewordsize;	\
    doublewordsize *ptrp = (doublewordsize*)(base);	\
  __asm__ volatile ("ldarx %0,%y1"		       	\
	   : "=r" (result)				\
	   : "Z" (*ptrp));				\
  result; })
#endif /* __powerpc64__ */

#define __stwcx(base, value) __extension__	\
  ({unsigned int result;			\
    typedef  struct {char a[4];} wordsize;	\
    wordsize *ptrp = (wordsize*)(base);		\
  __asm__ volatile ("stwcx. %2,%y1\n"		\
	   "\tmfocrf %0,0x80"			\
	   : "=r" (result),			\
	     "=Z" (*ptrp)			\
	   : "r" (value));			\
  ((result & 0x20000000) >> 29); })


#ifdef __powerpc64__
#define __stdcx(base, value) __extension__		\
  ({unsigned long long result;				\
    typedef  struct {char a[8];} doublewordsize;	\
    doublewordsize *ptrp = (doublewordsize*)(base);	\
  __asm__ volatile ("stdcx. %2,%y1\n"			\
	   "\tmfocrf %0,0x80"				\
	   : "=r" (result),				\
	     "=Z" (*ptrp)				\
	   : "r" (value));				\
  ((result & 0x20000000) >> 29); })
#endif /* __powerpc64__ */


/*
 * --- end extract from ppu_intrinics.h --
 */


void 
gc_jd_stack_init(gc_jd_stack_t *stack)
{
  stack->top = 0;
}
  

#ifdef __powerpc64__  // 64-bit mode

void 
gc_jd_stack_push(gc_jd_stack_t *stack, gc_job_desc_t *item)
{
  gc_eaddr_t	top;
  gc_eaddr_t	item_ea = ptr_to_ea(item);
  unsigned int	done;

  do {
    top = __ldarx(&stack->top);
    item->sys.next = top;
    smp_wmb();	      // order store of item->next before store of stack->top
    done = __stdcx(&stack->top, item_ea);
  } while (unlikely(done == 0));
}

gc_job_desc_t *
gc_jd_stack_pop(gc_jd_stack_t *stack)
{
  gc_eaddr_t	s;
  gc_eaddr_t	t;
  unsigned int	done;

  do {
    s  = __ldarx(&stack->top);
    if (s == 0)			/* stack's empty */
      return 0;
    t = ((gc_job_desc_t *) ea_to_ptr(s))->sys.next;
    done = __stdcx(&stack->top, t);
  } while (unlikely(done == 0));

  return ea_to_ptr(s);
}

#else  // 32-bit mode

/*
 * In 32-bit mode, gc_eaddr's will have the top 32-bits zero.
 * The ldarx/stdcx instructions aren't available in 32-bit mode,
 * thus we use lwarx/stwcx on the low 32-bits of the 64-bit addresses.
 * Since we're big-endian, the low 32-bits are at word offset 1.
 */
void 
gc_jd_stack_push(gc_jd_stack_t *stack, gc_job_desc_t *item)
{
  gc_eaddr_t	top;
  unsigned int	done;

  do {
    top = __lwarx((int32_t *)(&stack->top) + 1);
    item->sys.next = top;
    smp_wmb();	      // order store of item->sys.next before store of stack->top
    done = __stwcx((int32_t *)(&stack->top) + 1, item);
  } while (unlikely(done == 0));
}

gc_job_desc_t *
gc_jd_stack_pop(gc_jd_stack_t *stack)
{
  gc_eaddr_t	s;
  gc_eaddr_t	t;
  unsigned int	done;

  do {
    s  = __lwarx((int32_t *)(&stack->top) + 1);
    if (s == 0)			/* stack's empty */
      return 0;
    t = ((gc_job_desc_t *) ea_to_ptr(s))->sys.next;
    done = __stwcx((int32_t *)(&stack->top) + 1, (uint32_t) t);
  } while (unlikely(done == 0));

  return ea_to_ptr(s);
}

#endif