paul@vixie.UUCP (Paul Vixie Esq) (01/26/88)
Comp.sources.misc: Volume 2, Issue 16
Submitted-By: Paul Vixie Esq <paul@vixie.UUCP>
Archive-Name: overstrike
/* noback - convert lines with backspaces to multiple lines
* vix 16jun87 [made it leave lines containing ESC alone (for 'col -f')]
* vix 16dec86 [add test for CR as end-of-line so that files already
* in overstrike format won't blow up the buffer...]
* vix 10oct86 [written......again......sigh]
*/
#include <stdio.h>
#define MDEPTH 10
#define MWIDTH 256
#define MYBUFSIZ 2000
#define EOL 0x0A
#define CR 0x0D
#define TAB 0x09
#define BS 0x08
#define SPACE 0x20
#define ESC 0x1B
main()
{
int depth[MWIDTH], /* depth of stack for each position */
length[MDEPTH], /* number of positions used / level */
data[MDEPTH][MWIDTH], /* actual data, all positions/levels */
buffer[MYBUFSIZ+1], /* pre-scan buffer */
bufptr, /* buffer-pointer, what else? */
has_esc, /* flag: line has escape in it */
i, /* the inevitable generic integer */
ch, /* current character being processed */
pos, /* current position (0..MWIDTH-1) */
curdepth, /* depth of current position */
maxdepth, /* depth of deepest position's stack */
end_int; /* all useful variables end with ',' */
/* I feel gross today. how about a goto?
*/
next_line:
/* load a line into the pre-scan buffer
* (I call it that because it didn't used to be here)
*/
has_esc = 0;
i = 0;
do {
ch = getchar();
if (ch == ESC)
has_esc++;
if (i == MYBUFSIZ) {
fprintf(stderr, "noback: pre-scan buffer overflow\n");
exit(2);
}
buffer[i++] = ch;
} while (ch != EOL && ch != EOF);
buffer[i] = 0;
/* if the line has an escape in it, write it straight out and go back
* for another line. escapes mean that some variable number of chars
* following will not occupy a print position, and since we can't know
* how many chars that will be, we don't handle the situation.
*/
if (has_esc) {
i = 0;
do { putchar(buffer[i++]); }
while (buffer[i]);
goto next_line;
}
bufptr = 0;
ch = buffer[bufptr++];
/* we are beginning a line
*/
for (i = 0; i < MWIDTH; i++)
depth[i] = -1;
for (i = 0; i < MDEPTH; i++)
length[i] = 0;
maxdepth = -1;
pos = 0;
while (ch != EOF && ch != EOL)
{
/* on a backspace, we send the position back one,
* then we go get the next character.
*
* NOTE: backspace as first character on the line
* is ignored.
*/
if (ch == BS)
{
if (pos > 0)
pos -= 1;
ch = buffer[bufptr++];
continue;
}
/* on a carriage-return, we set the position back
* to the beginning of the line, then go back for
* the next character.
*/
if (ch == CR)
{
pos = 0;
ch = buffer[bufptr++];
continue;
}
/* on a tab, we skip to the tab position and continue.
*/
if (ch == TAB)
{
/* increment first or it won't move from a
* tab position.
*/
do {pos += 1;} while ((pos % 8) != 0);
ch = buffer[bufptr++];
continue;
}
/* a normal character.
* -> push onto stack for this position
* -> (conditionally initialize new line)
* -> adjust max-length for this line
* -> get next character
* -> continue
*/
curdepth = ++depth[pos];
if (curdepth > maxdepth)
{
maxdepth = curdepth;
for (i = 0; i < MWIDTH; i++)
data[curdepth][i] = SPACE;
}
data[curdepth][pos] = ch;
pos += 1;
if (pos > length[curdepth])
length[curdepth] = pos;
ch = buffer[bufptr++];
}
/* end of line or file. either way, dump the lines out.
* draw from the bottom up, so that the overstriking
* characters are drawn first. this is because on CRTs,
* spaces (used in lines after the first for positioning)
* are destructive.
*/
for (i = maxdepth; i >= 0; i--)
{
for (pos = 0; pos < length[i]; pos++)
putchar(data[i][pos]);
putchar(CR);
}
putchar(EOL);
if (ch != EOF)
goto next_line;
/* end of file. bye kids...
*/
}
--
Paul A Vixie Esq
paul%vixie@uunet.uu.net
{uunet,ptsfa,hoptoad}!vixie!paul
San Francisco, (415) 647-7023