/*       SCCS Id: @(#)oldcrtl.c   3.0      90/05/24
/*   	 Pat Rankin  May'90                                       */
/* VMS NetHack support, not needed for vms 4.6,4.7,or 5.x.        */

#ifdef VERYOLD_VMS
/*
 * The following routines are used by NetHack but were not available
 * from the C Run-Time Library (VAXCRTL) prior to VMS V4.6.
 *
 *      atexit, memcmp, memcpy, qsort, rename, vprintf, vsprintf
 *
 * Most of them are implemented here, but others will have to be worked
 * around in another fashion [such as '#define USE_OLDARGS' (even though
 * <varargs.h> is available) to avoid the need for vprintf & vsprintf].
 *
 */
#define REG register

#ifndef SUPPRESS_MEM_FUNCS
/* note: hand optimized for VAX (hardware pre-decrement & post-increment) */

/* void *memset(void *, int, size_t) -- fill chunk of memory.
*/
char *memset( dst, fil, cnt )
REG char *dst;
REG char  fil;
REG int   cnt;
{
    char *dst_p = dst;
    while ( --cnt >= 0 )
	*dst++ = fil;
    return dst_p;
}

/* void *memcpy(void *, const void *, size_t) -- copy chunk of memory.
*/
char *memcpy( dst, src, cnt )       /*[functionally equivalent to memmove()]*/
REG char *dst;
REG char *src;
REG int   cnt;
{
    char *dst_p = dst;
    if ( src == dst || cnt <= 0 ) {
	;       /* do nothing */
    } else if ( dst < src || dst >= src + cnt ) {
	while ( --cnt >= 0 )
	    *dst++ = *src++;
    } else {    /* work backwards */
	dst += cnt,  src += cnt;
	while ( --cnt >= 0 )
	    *--dst = *--src;
    }
    return dst_p;
}

/* void *memchr(const void *, int, size_t) -- search for a byte.
*/
char *memchr( buf, byt, len )
REG char *buf;
REG char  byt;
REG int   len;
{
    while ( --len >= 0 )
	if ( *buf++ == byt )    /* found */
	    return --buf;
    return (char *)0;       /* not found */
}

/* int memcmp(const void *, const void *, size_t) -- compare two chunks.
*/
int memcmp( buf1, buf2, len )
REG char *buf1;
REG char *buf2;
REG int   len;
{
    while ( --len >= 0 )
	if ( *buf1++ != *buf2++ )
	    return (*--buf1 - *--buf2);
    return 0;   /* buffers matched */
}
#endif /*!SUPPRESS_MEM_FUNCS*/


#ifndef SUPPRESS_ATEXIT
/* int atexit(void (*)(void)) -- register an exit handler.
*/
#define MAX_EXIT_FUNCS 32       /* arbitrary (32 matches VAX C v3.x docs) */
struct _ex_hndlr { long reserved, (*routine)(), arg_count, *arg1_addr; };
static int ex_cnt = 0;          /* number of handlers registered so far */
static struct { long dummy_arg; struct _ex_hndlr handler;   /*(black box)*/
       } ex_data[MAX_EXIT_FUNCS];       /* static handler data */

int atexit( function )
    int (*function)();          /* note: actually gets called with 1 arg */
{
    if ( ex_cnt < MAX_EXIT_FUNCS ) {
	ex_data[ex_cnt].dummy_arg = 0;  /* ultimately receives exit reason */
	ex_data[ex_cnt].handler.reserved  = 0;
	ex_data[ex_cnt].handler.routine   = function;
	ex_data[ex_cnt].handler.arg_count = 1;          /*(required)*/
	ex_data[ex_cnt].handler.arg1_addr = &ex_data[ex_cnt].dummy_arg;
	SYS$DCLEXH( &ex_data[ex_cnt].handler);  /* declare exit handler */
	return ++ex_cnt;        /*(non-zero)*/
    } else
	return 0;
}
#endif /*!SUPPRESS_ATEXIT*/


#ifndef SUPPRESS_RENAME
/* int rename(const char *, const char *) -- rename a file (on same device).
*/
#ifndef EVMSERR
#include <errno.h>
#define C$$TRANSLATE(status)    (errno = EVMSERR,  vaxc$errno = (status))
#endif

int rename( old_name, new_name )
    char *old_name;
    char *new_name;
{
    struct _dsc { int len; char *adr; } old_dsc, new_dsc;
    unsigned long status, LIB$RENAME_FILE();

    /* put strings into descriptors and call run-time library routine */
    old_dsc.len = strlen( old_dsc.adr = old_name );
    new_dsc.len = strlen( new_dsc.adr = new_name );
    status = LIB$RENAME_FILE( &old_dsc, &new_dsc);  /* omit optional args */
    if ( !(status & 1) ) {      /* even => failure */
	C$$TRANSLATE(status);
	return -1;
    } else                      /*  odd => success */
	return 0;
}
#endif /*!SUPPRESS_RENAME*/


#ifndef SUPPRESS_QSORT
/* void qsort(void *, size_t, size_t, int (*)()) -- sort arbitrary collection.
*/
void qsort( base, count, size, compare )
    char *base;
    int   count;
REG int   size;
    int (*compare)();
{
REG int   i, cmp;
REG char *next, *prev, *tmp = 0;
    char  wrk_buf[512], *malloc();      /* assume no alloca() available */

    /* just use a shuffle sort (tradeoff between efficiency & simplicity) */
    /*  [Optimal if already sorted; worst case when initially reversed.]  */
    for ( next = base, i = 1;  i < count;  i++ ) {
	prev = next,  next += size;             /* increment front pointer */
	if ( (cmp = (*compare)( next, prev)) < 0 ) {
	    /* found element out of order; move other(s) up then re-insert it */
	    if ( !tmp )  tmp = (size > sizeof wrk_buf ? malloc(size) : wrk_buf);
	    memcpy( tmp, next, size);           /* save smaller element */
	    while ( cmp < 0 ) {
		memcpy( prev + size, prev, size);   /* move larger elem. up */
		prev -= size;                   /* decrement back pointer */
		cmp = (prev >= base ? (*compare)( tmp, prev) : 0);
	    }
	    memcpy( prev + size, tmp, size);    /* restore small element */
	}
    }
    if ( tmp != 0 && tmp != wrk_buf )  free(tmp);
    return;
}
#endif /*!SUPPRESS_QSORT*/

#endif /*VERYOLD_VMS*/