/*

 * 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.

 */

#include "private/gc_priv.h"

/*

 * 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.

 */

STATIC bottom_index * GC_all_bottom_indices = 0;

                                /* Pointer to first (lowest addr) */

                                /* bottom_index.                  */

STATIC bottom_index * GC_all_bottom_indices_end = 0;

                                /* Pointer to last (highest addr) */

                                /* bottom_index.                  */

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

GC_INNER hdr * GC_find_header(ptr_t h)

{

#   ifdef HASH_TL

        hdr * result;

        GET_HDR(h, result);

        return(result);

#   else

        return(HDR_INNER(h));

#   endif

}

/* Handle a header cache miss.  Returns a pointer to the        */

/* header corresponding to p, if p can possibly be a valid      */

/* object pointer, and 0 otherwise.                             */

/* GUARANTEED to return 0 for a pointer past the first page     */

/* of an object unless both GC_all_interior_pointers is set     */

/* and p is in fact a valid object pointer.                     */

/* Never returns a pointer to a free hblk.                      */

GC_INNER hdr *

#ifdef PRINT_BLACK_LIST

  GC_header_cache_miss(ptr_t p, hdr_cache_entry *hce, ptr_t source)

#else

  GC_header_cache_miss(ptr_t p, hdr_cache_entry *hce)

#endif

{

  hdr *hhdr;

  HC_MISS();

  GET_HDR(p, hhdr);

  if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {

    if (GC_all_interior_pointers) {

      if (hhdr != 0) {

        ptr_t current = p;

        current = (ptr_t)HBLKPTR(current);

        do {

            current = current - HBLKSIZE*(word)hhdr;

            hhdr = HDR(current);

        } while(IS_FORWARDING_ADDR_OR_NIL(hhdr));

        /* current points to near the start of the large object */

        if (hhdr -> hb_flags & IGNORE_OFF_PAGE)

            return 0;

        if (HBLK_IS_FREE(hhdr)

            || p - current >= (ptrdiff_t)(hhdr->hb_sz)) {

            GC_ADD_TO_BLACK_LIST_NORMAL(p, source);

            /* Pointer past the end of the block */

            return 0;

        }

      } else {

        GC_ADD_TO_BLACK_LIST_NORMAL(p, source);

        /* And return zero: */

      }

      GC_ASSERT(hhdr == 0 || !HBLK_IS_FREE(hhdr));

      return hhdr;

      /* Pointers past the first page are probably too rare     */

      /* to add them to the cache.  We don't.                   */

      /* And correctness relies on the fact that we don't.      */

    } else {

      if (hhdr == 0) {

        GC_ADD_TO_BLACK_LIST_NORMAL(p, source);

      }

      return 0;

    }

  } else {

    if (HBLK_IS_FREE(hhdr)) {

      GC_ADD_TO_BLACK_LIST_NORMAL(p, source);

      return 0;

    } else {

      hce -> block_addr = (word)(p) >> LOG_HBLKSIZE;

      hce -> hce_hdr = hhdr;

      return hhdr;

    }

  }

}

/* 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.             */

GC_INNER ptr_t GC_scratch_alloc(size_t bytes)

{

    ptr_t result = scratch_free_ptr;

    size_t bytes_to_get;

    bytes = ROUNDUP_GRANULE_SIZE(bytes);

    for (;;) {

        scratch_free_ptr += bytes;

        if ((word)scratch_free_ptr <= (word)GC_scratch_end_ptr) {

            /* Unallocated space of scratch buffer has enough size. */

            return result;

        }

        if (bytes >= MINHINCR * HBLKSIZE) {

            bytes_to_get = ROUNDUP_PAGESIZE_IF_MMAP(bytes);

            result = (ptr_t)GET_MEM(bytes_to_get);

            GC_add_to_our_memory(result, bytes_to_get);

            /* Undo scratch free area pointer update; get memory directly. */

            scratch_free_ptr -= bytes;

            if (result != NULL) {

                /* Update end point of last obtained area (needed only  */

                /* by GC_register_dynamic_libraries for some targets).  */

                GC_scratch_last_end_ptr = result + bytes;

            }

            return result;

        }

        bytes_to_get = ROUNDUP_PAGESIZE_IF_MMAP(MINHINCR * HBLKSIZE);

                                                /* round up for safety */

        result = (ptr_t)GET_MEM(bytes_to_get);

        GC_add_to_our_memory(result, bytes_to_get);

        if (NULL == result) {

            WARN("Out of memory - trying to allocate requested amount"

                 " (%" WARN_PRIdPTR " bytes)...\n", (word)bytes);

            scratch_free_ptr -= bytes; /* Undo free area pointer update */

            bytes_to_get = ROUNDUP_PAGESIZE_IF_MMAP(bytes);

            result = (ptr_t)GET_MEM(bytes_to_get);

            GC_add_to_our_memory(result, bytes_to_get);

            return result;

        }

        /* Update scratch area pointers and retry.      */

        scratch_free_ptr = result;

        GC_scratch_end_ptr = scratch_free_ptr + bytes_to_get;

        GC_scratch_last_end_ptr = GC_scratch_end_ptr;

    }

}

static hdr * hdr_free_list = 0;

/* Return an uninitialized header */

static hdr * alloc_hdr(void)

{

    register hdr * result;

    if (hdr_free_list == 0) {

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

    } else {

        result = hdr_free_list;

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

    }

    return(result);

}

GC_INLINE void free_hdr(hdr * hhdr)

{

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

    hdr_free_list = hhdr;

}

#ifdef COUNT_HDR_CACHE_HITS

  /* Used for debugging/profiling (the symbols are externally visible). */

  word GC_hdr_cache_hits = 0;

  word GC_hdr_cache_misses = 0;

#endif

GC_INNER void GC_init_headers(void)

{

    register unsigned i;

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

    if (GC_all_nils == NULL) {

      GC_err_printf("Insufficient memory for GC_all_nils\n");

      EXIT();

    }

    BZERO(GC_all_nils, sizeof(bottom_index));

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

        GC_top_index[i] = GC_all_nils;

    }

}

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

/* Return FALSE on failure.                                             */

static GC_bool get_index(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

      word 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(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(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.  */

GC_INNER struct hblkhdr * GC_install_header(struct hblk *h)

{

    hdr * result;

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

    result = alloc_hdr();

    if (result) {

      SET_HDR(h, result);

#     ifdef USE_MUNMAP

        result -> hb_last_reclaimed = (unsigned short)GC_gc_no;

#     endif

    }

    return(result);

}

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

GC_INNER GC_bool GC_install_counts(struct hblk *h, size_t sz/* bytes */)

{

    struct hblk * hbp;

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

        word i = HBLK_PTR_DIFF(hbp, h);

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

    }

    return(TRUE);

}

/* Remove the header for block h */

GC_INNER void GC_remove_header(struct hblk *h)

{

    hdr **ha;

    GET_HDR_ADDR(h, ha);

    free_hdr(*ha);

    *ha = 0;

}

/* Remove forwarding counts for h */

GC_INNER void GC_remove_counts(struct hblk *h, size_t sz/* bytes */)

{

    register struct hblk * hbp;

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

        SET_HDR(hbp, 0);

    }

}

/* Apply fn to all allocated blocks */

/*VARARGS1*/

void GC_apply_to_all_blocks(void (*fn)(struct hblk *h, word client_data),

                            word client_data)

{

    signed_word j;

    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 (!HBLK_IS_FREE(index_p->index[j])) {

                    (*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 -= (signed_word)(index_p->index[j]);

             }

         }

     }

}

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

/* Return 0 if there is none.                           */

GC_INNER struct hblk * GC_next_used_block(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 (!HBLK_IS_FREE(hhdr)) {

                    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.              */

GC_INNER struct hblk * GC_prev_block(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);

}