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/*

 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers

 * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.

 * Copyright (c) 1996 by Silicon Graphics.  All rights reserved.

 *

 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED

 * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.

 *

 * Permission is hereby granted to use or copy this program

 * for any purpose,  provided the above notices are retained on all copies.

 * Permission to modify the code and to distribute modified code is granted,

 * provided the above notices are retained, and a notice that the code was

 * modified is included with the above copyright notice.

 */

/*

 * This implements:

 * 1. allocation of heap block headers

 * 2. A map from addresses to heap block addresses to heap block headers

 *

 * Access speed is crucial.  We implement an index structure based on a 2

 * level tree.

 */

# include "private/gc_priv.h"

bottom_index * GC_all_bottom_indices = 0;

                                /* Pointer to first (lowest addr) */

                                /* bottom_index.                  */

bottom_index * GC_all_bottom_indices_end = 0;

                                /* Pointer to last (highest addr) */

                                /* bottom_index.                  */

/* Non-macro version of header location routine */

hdr * GC_find_header(h)

ptr_t h;

{

#   ifdef HASH_TL

        register hdr * result;

        GET_HDR(h, result);

        return(result);

#   else

        return(HDR_INNER(h));

#   endif

}

/* Routines to dynamically allocate collector data structures that will */

/* never be freed.                                                       */

static ptr_t scratch_free_ptr = 0;

/* GC_scratch_last_end_ptr is end point of last obtained scratch area.  */

/* GC_scratch_end_ptr is end point of current scratch area.             */

ptr_t GC_scratch_alloc(bytes)

register word bytes;

{

    register ptr_t result = scratch_free_ptr;

#   ifdef ALIGN_DOUBLE

#       define GRANULARITY (2 * sizeof(word))

#   else

#       define GRANULARITY sizeof(word)

#   endif

    bytes += GRANULARITY-1;

    bytes &= ~(GRANULARITY-1);

    scratch_free_ptr += bytes;

    if (scratch_free_ptr <= GC_scratch_end_ptr) {

        return(result);

    }

    {

        word bytes_to_get = MINHINCR * HBLKSIZE;

        if (bytes_to_get <= bytes) {

          /* Undo the damage, and get memory directly */

            bytes_to_get = bytes;

#           ifdef USE_MMAP

                bytes_to_get += GC_page_size - 1;

                bytes_to_get &= ~(GC_page_size - 1);

#           endif

            result = (ptr_t)GET_MEM(bytes_to_get);

            scratch_free_ptr -= bytes;

            GC_scratch_last_end_ptr = result + bytes;

            return(result);

        }

        result = (ptr_t)GET_MEM(bytes_to_get);

        if (result == 0) {

#           ifdef PRINTSTATS

                GC_printf0("Out of memory - trying to allocate less\n");

#           endif

            scratch_free_ptr -= bytes;

            bytes_to_get = bytes;

#           ifdef USE_MMAP

                bytes_to_get += GC_page_size - 1;

                bytes_to_get &= ~(GC_page_size - 1);

#           endif

            return((ptr_t)GET_MEM(bytes_to_get));

        }

        scratch_free_ptr = result;

        GC_scratch_end_ptr = scratch_free_ptr + bytes_to_get;

        GC_scratch_last_end_ptr = GC_scratch_end_ptr;

        return(GC_scratch_alloc(bytes));

    }

}

static hdr * hdr_free_list = 0;

/* Return an uninitialized header */

static hdr * alloc_hdr()

{

    register hdr * result;

    if (hdr_free_list == 0) {

        result = (hdr *) GC_scratch_alloc((word)(sizeof(hdr)));

    } else {

        result = hdr_free_list;

        hdr_free_list = (hdr *) (result -> hb_next);

    }

    return(result);

}

static void free_hdr(hhdr)

hdr * hhdr;

{

    hhdr -> hb_next = (struct hblk *) hdr_free_list;

    hdr_free_list = hhdr;

}

hdr * GC_invalid_header;

#ifdef USE_HDR_CACHE

  word GC_hdr_cache_hits = 0;

  word GC_hdr_cache_misses = 0;

#endif

void GC_init_headers()

{

    register unsigned i;

    GC_all_nils = (bottom_index *)GC_scratch_alloc((word)sizeof(bottom_index));

    BZERO(GC_all_nils, sizeof(bottom_index));

    for (i = 0; i < TOP_SZ; i++) {

        GC_top_index[i] = GC_all_nils;

    }

    GC_invalid_header = alloc_hdr();

    GC_invalidate_map(GC_invalid_header);

}

/* Make sure that there is a bottom level index block for address addr  */

/* Return FALSE on failure.                                             */

static GC_bool get_index(addr)

word addr;

{

    word hi = (word)(addr) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);

    bottom_index * r;

    bottom_index * p;

    bottom_index ** prev;

    bottom_index *pi;

#   ifdef HASH_TL

      unsigned i = TL_HASH(hi);

      bottom_index * old;

      old = p = GC_top_index[i];

      while(p != GC_all_nils) {

          if (p -> key == hi) return(TRUE);

          p = p -> hash_link;

      }

      r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));

      if (r == 0) return(FALSE);

      BZERO(r, sizeof (bottom_index));

      r -> hash_link = old;

      GC_top_index[i] = r;

#   else

      if (GC_top_index[hi] != GC_all_nils) return(TRUE);

      r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));

      if (r == 0) return(FALSE);

      GC_top_index[hi] = r;

      BZERO(r, sizeof (bottom_index));

#   endif

    r -> key = hi;

    /* Add it to the list of bottom indices */

      prev = &GC_all_bottom_indices;    /* pointer to p */

      pi = 0;                            /* bottom_index preceding p */

      while ((p = *prev) != 0 && p -> key < hi) {

        pi = p;

        prev = &(p -> asc_link);

      }

      r -> desc_link = pi;

      if (0 == p) {

        GC_all_bottom_indices_end = r;

      } else {

        p -> desc_link = r;

      }

      r -> asc_link = p;

      *prev = r;

    return(TRUE);

}

/* Install a header for block h.        */

/* The header is uninitialized.         */

/* Returns the header or 0 on failure.  */

struct hblkhdr * GC_install_header(h)

register struct hblk * h;

{

    hdr * result;

    if (!get_index((word) h)) return(0);

    result = alloc_hdr();

    SET_HDR(h, result);

#   ifdef USE_MUNMAP

        result -> hb_last_reclaimed = GC_gc_no;

#   endif

    return(result);

}

/* Set up forwarding counts for block h of size sz */

GC_bool GC_install_counts(h, sz)

register struct hblk * h;

register word sz; /* bytes */

{

    register struct hblk * hbp;

    register int i;

    for (hbp = h; (char *)hbp < (char *)h + sz; hbp += BOTTOM_SZ) {

        if (!get_index((word) hbp)) return(FALSE);

    }

    if (!get_index((word)h + sz - 1)) return(FALSE);

    for (hbp = h + 1; (char *)hbp < (char *)h + sz; hbp += 1) {

        i = HBLK_PTR_DIFF(hbp, h);

        SET_HDR(hbp, (hdr *)(i > MAX_JUMP? MAX_JUMP : i));

    }

    return(TRUE);

}

/* Remove the header for block h */

void GC_remove_header(h)

register struct hblk * h;

{

    hdr ** ha;

    GET_HDR_ADDR(h, ha);

    free_hdr(*ha);

    *ha = 0;

}

/* Remove forwarding counts for h */

void GC_remove_counts(h, sz)

register struct hblk * h;

register word sz; /* bytes */

{

    register struct hblk * hbp;

    for (hbp = h+1; (char *)hbp < (char *)h + sz; hbp += 1) {

        SET_HDR(hbp, 0);

    }

}

/* Apply fn to all allocated blocks */

/*VARARGS1*/

void GC_apply_to_all_blocks(fn, client_data)

void (*fn) GC_PROTO((struct hblk *h, word client_data));

word client_data;

{

    register int j;

    register bottom_index * index_p;

    for (index_p = GC_all_bottom_indices; index_p != 0;

         index_p = index_p -> asc_link) {

        for (j = BOTTOM_SZ-1; j >= 0;) {

            if (!IS_FORWARDING_ADDR_OR_NIL(index_p->index[j])) {

                if (index_p->index[j]->hb_map != GC_invalid_map) {

                    (*fn)(((struct hblk *)

                              (((index_p->key << LOG_BOTTOM_SZ) + (word)j)

                               << LOG_HBLKSIZE)),

                          client_data);

                }

                j--;

             } else if (index_p->index[j] == 0) {

                j--;

             } else {

                j -= (word)(index_p->index[j]);

             }

         }

     }

}

/* Get the next valid block whose address is at least h */

/* Return 0 if there is none.                           */

struct hblk * GC_next_used_block(h)

struct hblk * h;

{

    register bottom_index * bi;

    register word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);

    GET_BI(h, bi);

    if (bi == GC_all_nils) {

        register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);

        bi = GC_all_bottom_indices;

        while (bi != 0 && bi -> key < hi) bi = bi -> asc_link;

        j = 0;

    }

    while(bi != 0) {

        while (j < BOTTOM_SZ) {

            hdr * hhdr = bi -> index[j];

            if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {

                j++;

            } else {

                if (hhdr->hb_map != GC_invalid_map) {

                    return((struct hblk *)

                              (((bi -> key << LOG_BOTTOM_SZ) + j)

                               << LOG_HBLKSIZE));

                } else {

                    j += divHBLKSZ(hhdr -> hb_sz);

                }

            }

        }

        j = 0;

        bi = bi -> asc_link;

    }

    return(0);

}

/* Get the last (highest address) block whose address is        */

/* at most h.  Return 0 if there is none.                       */

/* Unlike the above, this may return a free block.              */

struct hblk * GC_prev_block(h)

struct hblk * h;

{

    register bottom_index * bi;

    register signed_word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);

    GET_BI(h, bi);

    if (bi == GC_all_nils) {

        register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);

        bi = GC_all_bottom_indices_end;

        while (bi != 0 && bi -> key > hi) bi = bi -> desc_link;

        j = BOTTOM_SZ - 1;

    }

    while(bi != 0) {

        while (j >= 0) {

            hdr * hhdr = bi -> index[j];

            if (0 == hhdr) {

                --j;

            } else if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {

                j -= (signed_word)hhdr;

            } else {

                return((struct hblk *)

                          (((bi -> key << LOG_BOTTOM_SZ) + j)

                               << LOG_HBLKSIZE));

            }

        }

        j = BOTTOM_SZ - 1;

        bi = bi -> desc_link;

    }

    return(0);

}