source: trunk/minix/commands/elvis/recycle.c@ 12

/* recycle.c */

/* Author:
 *      Steve Kirkendall
 *      14407 SW Teal Blvd. #C
 *      Beaverton, OR 97005
 *      kirkenda@cs.pdx.edu
 */


/* This file contains the functions perform garbage collection and allocate
 * reusable blocks.
 */

#include "config.h"
#include "vi.h"

#ifndef NO_RECYCLE
/* this whole file would have be skipped if NO_RECYCLE is defined */


#define BTST(bitno, byte)       ((byte) & (1 << (bitno)))
#define BSET(bitno, byte)       ((byte) |= (1 << (bitno)))
#define BCLR(bitno, byte)       ((byte) &= ~(1 << (bitno)))

#define TST(blkno)              ((blkno) < MAXBIT ? BTST((blkno) & 7, bitmap[(blkno) >> 3]) : 1)
#define SET(blkno)              if ((blkno) < MAXBIT) BSET((blkno) & 7, bitmap[(blkno) >> 3])
#define CLR(blkno)              if ((blkno) < MAXBIT) BCLR((blkno) & 7, bitmap[(blkno) >> 3])

/* bitmap of free blocks in first 4096k of tmp file */
static unsigned char bitmap[512];
#define MAXBIT  (sizeof bitmap << 3)

/* this function locates all free blocks in the current tmp file */
void garbage()
{
        int     i;
        BLK     oldhdr;

        /* start by assuming every block is free */
        for (i = 0; i < sizeof bitmap; i++)
        {
                bitmap[i] = 255;
        }

        /* header blocks aren't free */
#ifndef lint
        CLR(0);
        CLR(1);
#endif

        /* blocks needed for current hdr aren't free */
        for (i = 1; i < MAXBLKS; i++)
        {
                CLR(hdr.n[i]);
        }

        /* blocks needed for undo version aren't free */
        lseek(tmpfd, 0L, 0);
        if (read(tmpfd, &oldhdr, (unsigned)sizeof oldhdr) != sizeof oldhdr)
        {
                msg("garbage() failed to read oldhdr??");
                for (i = 0; i < sizeof bitmap; i++)
                {
                        bitmap[i] = 0;
                }
                return;
        }
        for (i = 1; i < MAXBLKS; i++)
        {
                CLR(oldhdr.n[i]);
        }

        /* blocks needed for cut buffers aren't free */
        for (i = cutneeds(&oldhdr) - 1; i >= 0; i--)
        {
                CLR(oldhdr.n[i]);
        }
}

/* This function allocates the first available block in the tmp file */
long allocate()
{
        int     i;
        long    offset;

        /* search for the first byte with a free bit set */
        for (i = 0; i < sizeof bitmap && bitmap[i] == 0; i++)
        {
        }

        /* if we hit the end of the bitmap, return the end of the file */
        if (i == sizeof bitmap)
        {
                offset = lseek(tmpfd, 0L, 2);
        }
        else /* compute the offset for the free block */
        {
                for (i <<= 3; TST(i) == 0; i++)
                {
                }
                offset = (long)i * (long)BLKSIZE;

                /* mark the block as "allocated" */
                CLR(i);
        }

        return offset;
}

#endif

#ifdef DEBUG
# include <stdio.h>
# undef malloc
# undef free
# define MEMMAGIC 0x19f72cc0L
# define MAXALLOC 800
static char *allocated[MAXALLOC];
static char *fromfile[MAXALLOC];
static int  fromline[MAXALLOC]; 
static int  sizes[MAXALLOC];

char *dbmalloc(size, file, line)
        int     size;
        char    *file;
        int     line;
{
        char    *ret;
        int     i;

        size = size + sizeof(long) - (size % sizeof(long));
        ret = (char *)malloc(size + 2 * sizeof(long)) + sizeof(long);
        for (i = 0; i < MAXALLOC && allocated[i]; i++)
        {
        }
        if (i == MAXALLOC)
        {
                endwin();
                fprintf(stderr, "\r\n%s(%d): Too many malloc calls!\n", file, line);
                abort();
        }
        sizes[i] = size/sizeof(long);
        allocated[i] = ret;
        fromfile[i] = file;
        fromline[i] = line;
        ((long *)ret)[-1] = MEMMAGIC;
        ((long *)ret)[sizes[i]] = MEMMAGIC;
        return ret;
}

dbfree(ptr, file, line)
        char    *ptr;
        char    *file;
        int     line;
{
        int     i;

        for (i = 0; i < MAXALLOC && allocated[i] != ptr; i++)
        {
        }
        if (i == MAXALLOC)
        {
                endwin();
                fprintf(stderr, "\r\n%s(%d): attempt to free mem that wasn't allocated\n", file, line);
                abort();
        }
        allocated[i] = (char *)0;
        if (((long *)ptr)[-1] != MEMMAGIC)
        {
                endwin();
                fprintf(stderr, "\r\n%s(%d): underflowed malloc space, allocated at %s(%d)\n", file, line, fromfile[i], fromline[i]);
                abort();
        }
        if (((long *)ptr)[sizes[i]] != MEMMAGIC)
        {
                endwin();
                fprintf(stderr, "\r\n%s(%d): overflowed malloc space, allocated at %s(%d)\n", file, line, fromfile[i], fromline[i]);
                abort();
        }
        free(ptr - sizeof(long));
}
#endif