minix/commands/elvis/tinyprnt.c
2009-11-09 10:26:00 +00:00

230 lines
4.7 KiB
C

/* tinyprnt.c */
#if OSK
#define sprintf Sprintf
#endif
/* This is a limited version of sprintf(). It is useful for Minix-PC and
* Coherent-286 because those systems are both limited to 64k+64k and the
* standard sprintf() is just too damn big.
*
* It should also be useful for OS-9 because OS-9's sprintf() doesn't
* understand the true meaning of asterisks in a format string. This one
* does.
*/
/* Place-holders in format strings look like "%<pad><clip><type>".
*
* The <pad> adds space to the front (or, if negative, to the back) of the
* output value, to pad it to a given width. If <pad> is absent, then 0 is
* assumed. If <pad> is an asterisk, then the next argument is assumed to
* be an (int) which used as the pad width.
*
* The <clip> string can be absent, in which case no clipping is done.
* However, if it is present, then it should be either a "." followed by
* a number, or a "." followed by an asterisk. The asterisk means that the
* next argument is an (int) which should be used as the pad width. Clipping
* only affects strings; for other data types it is ignored.
*
* The <type> is one of "s" for strings, "c" for characters (really ints that
* are assumed to be legal char values), "d" for ints, "ld" for long ints, or
* "%" to output a percent sign.
*/
/* NOTE: Variable argument lists are handled by direct stack-twiddling. Sorry! */
static void cvtnum(buf, num, base)
char *buf; /* where to store the number */
unsigned long num; /* the number to convert */
int base; /* either 8, 10, or 16 */
{
static char digits[] = "0123456789abcdef";
unsigned long tmp;
/* if the number is 0, then just stuff a "0" into the buffer */
if (num == 0L)
{
buf[0] = '0';
buf[1] = '\0';
return;
}
/* use tmp to figure out how many digits we'll need */
for (tmp = num; tmp > 0; tmp /= base)
{
buf++;
}
/* mark the spot that will be the end of the string */
*buf = '\0';
/* generate all digits, as needed */
for (tmp = num; tmp > 0; tmp /= base)
{
*--buf = digits[tmp % base];
}
}
int sprintf(buf, fmt, argref)
char *buf; /* where to deposit the formatted output */
char *fmt; /* the format string */
int argref; /* the first argument is located at &argref */
{
char *argptr;/* pointer to next argument on the stack */
int pad; /* value of the pad string */
int clip; /* value of the clip string */
long num; /* a binary number being converted to ASCII digits */
long digit; /* used during conversion */
char *src, *dst;
/* make argptr point to the first argument after the format string */
argptr = (char *)&argref;
/* loop through the whole format string */
while (*fmt)
{
/* if not part of a place-holder, then copy it literally */
if (*fmt != '%')
{
*buf++ = *fmt++;
continue;
}
/* found a place-holder! Get <pad> value */
fmt++;
if ('*' == *fmt)
{
pad = *((int *)argptr)++;
fmt++;
}
else if (*fmt == '-' || (*fmt >= '0' && *fmt <= '9'))
{
pad = atol(fmt);
do
{
fmt++;
} while (*fmt >= '0' && *fmt <= '9');
}
else
{
pad = 0;
}
/* get a <clip> value */
if (*fmt == '.')
{
fmt++;
if ('*' == *fmt)
{
clip = *((int *)argptr)++;
fmt++;
}
else if (*fmt >= '0' && *fmt <= '9')
{
clip = atol(fmt);
do
{
fmt++;
} while (*fmt >= '0' && *fmt <= '9');
}
}
else
{
clip = 0;
}
/* handle <type>, possibly noticing <clip> */
switch (*fmt++)
{
case 'c':
buf[0] = *((int *)argptr)++;
buf[1] = '\0';
break;
case 's':
src = *((char **)argptr)++;
if (!src)
{
src = "(null)";
}
if (clip)
{
strncpy(buf, src, clip);
buf[clip] = '\0';
}
else
{
strcpy(buf, src);
}
break;
case 'l':
fmt++; /* to skip the "d" in "%ld" */
num = *((long *)argptr)++;
dst = buf;
if (num < 0)
{
*dst++ = '-';
num = -num;
}
cvtnum(dst, num, 10);
break;
case 'x':
num = *((int *)argptr)++;
cvtnum(buf, num, 16);
break;
case 'd':
num = *((int *)argptr)++;
dst = buf;
if (num < 0)
{
*dst++ = '-';
num = -num;
}
cvtnum(dst, num, 10);
break;
default:
buf[0] = fmt[-1];
buf[1] = '\0';
}
/* now fix the padding, if the value is too short */
clip = strlen(buf);
if (pad < 0)
{
/* add spaces after the value */
pad = -pad - clip;
for (buf += clip; pad > 0; pad--)
{
*buf++ = ' ';
}
*buf = '\0';
}
else
{
/* add spaces before the value */
pad -= clip;
if (pad > 0)
{
src = buf + clip;
dst = src + pad;
*dst = '\0';
while (src > buf)
{
*--dst = *--src;
}
while (dst > buf)
{
*--dst = ' ';
}
}
buf += strlen(buf);
}
}
/* mark the end of the output string */
*buf = '\0';
}