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#include "gbos.h"
/* more [file]: page a file (or stdin) one screenful at a time.
*
* The terminal is 40x18, so anything longer than a screen scrolls off before
* you can read it (try `ls` on a full disk, or `cat` on a wget dump). This
* prints 17 lines, then paints a --More-- bar and waits for a keypress:
* SELECT opens the on-screen keyboard, any key pages forward, 'q' quits.
*
* Keys come from pollin()/pollcon(), NOT stdin - so `cat file | more` still
* has a keyboard even though its stdin is the pipe. (pollcon also means the
* host can drive it over the link with tools/gbtype.) */
#define PAGE 17 /* TROWS - 1: leave a row for the bar */
#define TCOLS 40
static void sgr(unsigned char n) { /* emit ESC [ n m */
putc(27);
putc('[');
putu(n);
putc('m');
}
/* show the bar, block until a key arrives; 0 = the user asked to quit */
static unsigned char waitkey(void) {
unsigned char c;
sgr(44);
sgr(37); /* white on blue */
puts("--More--");
sgr(0);
for (;;) {
c = pollin(); /* on-screen keyboard */
if (!c) c = pollcon(); /* link-injected console bytes */
if (c) break;
yield(); /* cooperative: let other procs run */
}
puts("\r \r"); /* wipe the bar, stay on the same row */
return (c == 'q' || c == 'Q') ? 0 : 1;
}
void main(void) {
char *argv[4];
unsigned char argc = argv_parse(argv, 4);
unsigned char fd = NOFD, rows = 0, col = 0;
int ch;
if (argc > 0 && argv[0][0] != '-') {
fd = open(argv[0], O_READ);
if (fd == EISDIR) {
puts("more: is a directory");
nl();
sexit(2);
}
if (fd == NOFD) {
puts("more: no such file");
nl();
sexit(2);
}
}
for (;;) {
if (fd == NOFD) {
char c = readc();
ch = (c == EOF) ? -1 : c;
} else ch = fgetc(fd);
if (ch < 0) break;
putc((char)ch);
/* count screen rows, not input lines: a 100-char line wraps to three */
if (ch == '\n') {
rows++;
col = 0;
} else if (ch != '\r' && ++col == TCOLS) {
rows++;
col = 0;
}
if (rows >= PAGE) {
if (!waitkey()) break;
rows = 0;
}
}
if (fd != NOFD) close(fd);
}
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