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/*
Unlike "vcs", reading "vcsa" from offset 0 returns a buffer with a 4-byte
header containing (as I recall) rows, cols, cur_col, cur_row, in that order.
When placing new data in the buffer, offset 4 should be treated as 0, but
the whole buffer, header included, should be written back from 0.
*/
/*
Here's my "port" of Borland C's gettext() and puttext(), using /dev/vcsa0.
They read/write rectangular areas of the screen.
written by Bob McCracken
*/
#include <stdio.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <termios.h>
#include <stdlib.h>
#include <fcntl.h>
#define DEV "/dev/vcsa0"
#ifndef uchar
#define uchar unsigned char
#endif
int GetText (uchar *buf, int y1, int x1, int y2, int x2)
{
int Bpr, p, h, v, x, y;
uchar *M, *Mem;
struct winsize W;
ioctl (0, TIOCGWINSZ, &W);
/*
Borland's version defaults to the real full-screen size if the
parms are invalid. Not liking that, I return an error, instead.
*/
if (x1 < 0 || y1 < 0 || x2 >= W.ws_col || y2 >= W.ws_row ||
x1 > x2 || y1 > y2) return -1;
if ((y = open (DEV, 0)) < 0) return -1;
Bpr = (W.ws_col << 1); /* bytes-per-row */
x = (Bpr * W.ws_row) + 4; /* Include 4-byte header in buffer size */
Mem = (uchar *) malloc (x); /* Ought to check for failure here! */
M = Mem + 4; /* Point M to start of actual screen data */
read (y, Mem, x); close (y);
/*
"Rectangularize" the screen data and copy to caller's buffer ..
*/
v = y2-y1+1; h = (x2-x1+1) << 1; p = (y1 * Bpr) + (x1 << 1);
for (x = y = 0; y < v; y++, p += Bpr, x += h) memcpy (buf+x, M+p, h);
free (Mem); return 0;
}
/* Same as above, in reverse ... */
int PutText (uchar *buf, int y1, int x1, int y2, int x2)
{
int fd, ss, Bpr, p, h, v, x, y;
uchar *M, *Mem;
struct winsize W;
ioctl (0, TIOCGWINSZ, &W);
if (x1 < 0 || y1 < 0 || x2 >= W.ws_col || y2 >= W.ws_row ||
x1 > x2 || y1 > y2) return -1;
if ((fd = open (DEV, 2)) < 0) return -1;
Bpr = (W.ws_col << 1);
ss = (Bpr * W.ws_row) + 4;
Mem = (uchar *) malloc (ss);
M = Mem + 4;
/* Get current screen contents and update with caller's "rectangle" */
read (fd, Mem, ss); lseek (fd, 0, 0);
v = y2-y1+1; h = (x2-x1+1) << 1; p = (y1 * Bpr) + (x1 << 1);
for (x = y = 0; y < v; y++, p += Bpr, x += h) memcpy (M+p, buf+x, h);
write (fd, Mem, ss); close (fd);
free (Mem); return 0;
}
/* Usage example: Change background color of a small area. */
#ifdef TEST_GETPUT
#define BGND 0x4F /* white on red */
#define Y1 6
#define X1 10
#define Y2 12
#define X2 39
#define XLEN (X2-X1+1)
#define YLEN (Y2-Y1+1)
#define BSIZE ((XLEN<<1)*YLEN)
uchar scrn [BSIZE];
void main()
{
int x;
if (GetText (scrn, Y1,X1, Y2,X2) < 0) printf ("oops"); else
{
for (x = 1; x < BSIZE; x += 2) scrn[x] = BGND;
PutText (scrn, Y1,X1, Y2,X2);
}
}
#endif
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