/*
   Copyright (C) 2009 Red Hat, Inc.

   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 holder nor the names of its
         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 HOLDER 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
   HOLDER 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.
*/


#ifndef _H_RING_
#define _H_RING_


#define MSB_MASK4(x)        \
    (((x) & 0x8) ? 0x8 :    \
     ((x) & 0x4) ? 0x4 :    \
     ((x) & 0x2) ? 0x2 :    \
     ((x) & 0x1) ? 0x1 : 0)

#define MSB_MASK8(x) \
    (((x) & 0xf0) ? MSB_MASK4((x) >> 4) << 4 : MSB_MASK4(x))

#define MSB_MASK16(x) \
    (((x) & 0xff00) ? MSB_MASK8((x) >> 8) << 8 : MSB_MASK8(x))

#define MSB_MASK(x) \
    (((x) & 0xffff0000) ? MSB_MASK16((x) >> 16) << 16 : MSB_MASK16(x))

#define POWER2_ALIGN(x) MSB_MASK((x) * 2 - 1)


#define _TOSHIFT_4(x)      \
    (((x) & 0x8) ? 3 :     \
     ((x) & 0x4) ? 2 :     \
     ((x) & 0x2) ? 1 : 0)

#define _TOSHIFT_8(x) \
    (((x) & 0xf0) ? _TOSHIFT_4((x) >> 4) + 4 : _TOSHIFT_4(x))

#define _TOSHIFT_16(x) \
    (((x) & 0xff00) ? _TOSHIFT_8((x) >> 8) + 8 : _TOSHIFT_8(x))

#define PAWER2_TO_SHIFT(x) \
    (((x) & 0xffff0000) ? _TOSHIFT_16((x) >> 16) + 16 : _TOSHIFT_16(x))



#define RING_DECLARE(name, el_type, size)               \
typedef struct ATTR_PACKED name##_ring_el {             \
    union {                                             \
        el_type el;                                     \
        UINT8 data[POWER2_ALIGN(sizeof(el_type))];      \
    } ;                                                 \
} name##_ring_el;                                       \
                                                        \
typedef struct ATTR_PACKED name {                       \
    UINT32 num_items;                                   \
    UINT32 prod;                                        \
    UINT32 notify_on_prod;                              \
    UINT32 cons;                                        \
    UINT32 notify_on_cons;                              \
    name##_ring_el items[POWER2_ALIGN(size)];           \
} name;


#define RING_INIT(r)                                                \
    (r)->num_items = sizeof((r)->items) >>                          \
                        PAWER2_TO_SHIFT(sizeof((r)->items[0]));     \
    (r)->prod = (r)->cons = 0;                                      \
    (r)->notify_on_prod = 1;                                        \
    (r)->notify_on_cons = 0;


#define RING_INDEX_MASK(r) ((r)->num_items - 1)

#define RING_IS_PACKED(r) (sizeof((r)->items[0]) == sizeof((r)->items[0]).el)

#define RING_IS_EMPTY(r) ((r)->cons == (r)->prod)

#define RING_IS_FULL(r) (((r)->prod - (r)->cons) == (r)->num_items)

#define RING_PROD_ITEM(r) (&(r)->items[(r)->prod & RING_INDEX_MASK(r)].el)

#define RING_PROD_WAIT(r, wait)                 \
    if (((wait) = RING_IS_FULL(r))) {           \
        (r)->notify_on_cons = (r)->cons + 1;    \
        mb();	                                \
        (wait) = RING_IS_FULL(r);               \
    }

#define RING_PUSH(r, notify)                    \
    (r)->prod++;                                \
    mb();                                       \
    (notify) = (r)->prod == (r)->notify_on_prod;


#define RING_CONS_ITEM(r) (&(r)->items[(r)->cons & RING_INDEX_MASK(r)].el)

#define RING_CONS_WAIT(r, wait)                 \
    if (((wait) = RING_IS_EMPTY(r))) {          \
        (r)->notify_on_prod = (r)->prod + 1;    \
        mb();                                   \
        (wait) = RING_IS_EMPTY(r);              \
    }

#define RING_POP(r, notify)                         \
    (r)->cons++;                                    \
    mb();                                           \
    (notify) = (r)->cons == (r)->notify_on_cons;



#endif