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/*

 * Copyright (c) 1992-1994 by Xerox Corporation.  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.

 */

/* Boehm, March 29, 1995 12:51 pm PST */

# ifdef CHECKSUMS

# include "private/gc_priv.h"

/* This is debugging code intended to verify the results of dirty bit   */

/* computations. Works only in a single threaded environment.           */

/* We assume that stubborn objects are changed only when they are       */

/* enabled for writing.  (Certain kinds of writing are actually         */

/* safe under other conditions.)                                        */

# define NSUMS 10000

# define OFFSET 0x10000

typedef struct {

        GC_bool new_valid;

        word old_sum;

        word new_sum;

        struct hblk * block;    /* Block to which this refers + OFFSET  */

                                /* to hide it from collector.           */

} page_entry;

page_entry GC_sums [NSUMS];

word GC_checksum(h)

struct hblk *h;

{

    register word *p = (word *)h;

    register word *lim = (word *)(h+1);

    register word result = 0;

    while (p < lim) {

        result += *p++;

    }

    return(result | 0x80000000 /* doesn't look like pointer */);

}

# ifdef STUBBORN_ALLOC

/* Check whether a stubborn object from the given block appears on      */

/* the appropriate free list.                                           */

GC_bool GC_on_free_list(h)

struct hblk *h;

{

    register hdr * hhdr = HDR(h);

    register int sz = hhdr -> hb_sz;

    ptr_t p;

    if (sz > MAXOBJSZ) return(FALSE);

    for (p = GC_sobjfreelist[sz]; p != 0; p = obj_link(p)) {

        if (HBLKPTR(p) == h) return(TRUE);

    }

    return(FALSE);

}

# endif

int GC_n_dirty_errors;

int GC_n_changed_errors;

int GC_n_clean;

int GC_n_dirty;

void GC_update_check_page(h, index)

struct hblk *h;

int index;

{

    page_entry *pe = GC_sums + index;

    register hdr * hhdr = HDR(h);

    struct hblk *b;

    if (pe -> block != 0 && pe -> block != h + OFFSET) ABORT("goofed");

    pe -> old_sum = pe -> new_sum;

    pe -> new_sum = GC_checksum(h);

#   if !defined(MSWIN32) && !defined(MSWINCE)

        if (pe -> new_sum != 0x80000000 && !GC_page_was_ever_dirty(h)) {

            GC_printf1("GC_page_was_ever_dirty(0x%lx) is wrong\n",

                       (unsigned long)h);

        }

#   endif

    if (GC_page_was_dirty(h)) {

        GC_n_dirty++;

    } else {

        GC_n_clean++;

    }

    b = h;

    while (IS_FORWARDING_ADDR_OR_NIL(hhdr) && hhdr != 0) {

        b -= (word)hhdr;

        hhdr = HDR(b);

    }

    if (pe -> new_valid

        && hhdr != 0 && hhdr -> hb_descr != 0 /* may contain pointers */

        && pe -> old_sum != pe -> new_sum) {

        if (!GC_page_was_dirty(h) || !GC_page_was_ever_dirty(h)) {

            /* Set breakpoint here */GC_n_dirty_errors++;

        }

#       ifdef STUBBORN_ALLOC

          if ( hhdr -> hb_map != GC_invalid_map

            && hhdr -> hb_obj_kind == STUBBORN

            && !GC_page_was_changed(h)

            && !GC_on_free_list(h)) {

            /* if GC_on_free_list(h) then reclaim may have touched it   */

            /* without any allocations taking place.                    */

            /* Set breakpoint here */GC_n_changed_errors++;

          }

#       endif

    }

    pe -> new_valid = TRUE;

    pe -> block = h + OFFSET;

}

word GC_bytes_in_used_blocks;

void GC_add_block(h, dummy)

struct hblk *h;

word dummy;

{

   register hdr * hhdr = HDR(h);

   register bytes = WORDS_TO_BYTES(hhdr -> hb_sz);

   bytes += HBLKSIZE-1;

   bytes &= ~(HBLKSIZE-1);

   GC_bytes_in_used_blocks += bytes;

}

void GC_check_blocks()

{

    word bytes_in_free_blocks = GC_large_free_bytes;

    GC_bytes_in_used_blocks = 0;

    GC_apply_to_all_blocks(GC_add_block, (word)0);

    GC_printf2("GC_bytes_in_used_blocks = %ld, bytes_in_free_blocks = %ld ",

                GC_bytes_in_used_blocks, bytes_in_free_blocks);

    GC_printf1("GC_heapsize = %ld\n", GC_heapsize);

    if (GC_bytes_in_used_blocks + bytes_in_free_blocks != GC_heapsize) {

        GC_printf0("LOST SOME BLOCKS!!\n");

    }

}

/* Should be called immediately after GC_read_dirty and GC_read_changed. */

void GC_check_dirty()

{

    register int index;

    register unsigned i;

    register struct hblk *h;

    register ptr_t start;

    GC_check_blocks();

    GC_n_dirty_errors = 0;

    GC_n_changed_errors = 0;

    GC_n_clean = 0;

    GC_n_dirty = 0;

    index = 0;

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

        start = GC_heap_sects[i].hs_start;

        for (h = (struct hblk *)start;

             h < (struct hblk *)(start + GC_heap_sects[i].hs_bytes);

             h++) {

             GC_update_check_page(h, index);

             index++;

             if (index >= NSUMS) goto out;

        }

    }

out:

    GC_printf2("Checked %lu clean and %lu dirty pages\n",

              (unsigned long) GC_n_clean, (unsigned long) GC_n_dirty);

    if (GC_n_dirty_errors > 0) {

        GC_printf1("Found %lu dirty bit errors\n",

                   (unsigned long)GC_n_dirty_errors);

    }

    if (GC_n_changed_errors > 0) {

        GC_printf1("Found %lu changed bit errors\n",

                   (unsigned long)GC_n_changed_errors);

        GC_printf0("These may be benign (provoked by nonpointer changes)\n");

#       ifdef THREADS

            GC_printf0(

            "Also expect 1 per thread currently allocating a stubborn obj.\n");

#       endif

    }

}

# else

extern int GC_quiet;

        /* ANSI C doesn't allow translation units to be empty.  */

        /* So we guarantee this one is nonempty.                */

# endif /* CHECKSUMS */