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The C Users' Group Library 1994 August
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wc-cdrom-cusersgrouplibrary-1994-08.iso
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v_09_07
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9n07039a
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1990-12-31
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4KB
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113 lines
/* A simple function for line input */
/* alternate version using BIOS and direct screen access */
/* compiled with Turbo C 2.0 */
/* Philip J. Erdelsky - 01 JAN 1991 */
/* object code may be used freely */
static int key() {
int k = bioskey(0);
return (k&0xFF)!=0 ? k&0xFF : k;
}
int line_input(int far *screen, char *text, int text_length,
int display_length) {
/* start display as though operator had struck Home or End key */
int k = 0x4700; /* Home 0x4700 or End 0x4F00 */
int finished = 0;
int cursor_position;
int position_within_text;
while (1) {
switch (k) {
/* finish line input and exit if k==0x000D (Enter key) */
/* other terminating keys could be added, if desired */
case 0x000D:
finished = 1;
/* fall through to next case */
/* move cursor to left end of text if k==0x4700 (Home key) */
case 0x4700:
cursor_position = position_within_text = 0;
break;
/* move cursor to right end of text if k==0x4F00 (End key) */
case 0x4F00:
position_within_text = strlen(text);
cursor_position =
position_within_text<display_length ? position_within_text :
display_length-1;
break;
/* move cursor left one place if k==0x4B00 (left arrow key) */
case 0x4B00:
if (position_within_text>0) {
position_within_text--;
if (cursor_position>0) cursor_position--;
}
break;
/* move cursor right one place if k==0x4D00 (right arrow key) */
case 0x4D00:
if (position_within_text<strlen(text)) {
position_within_text++;
if (cursor_position<display_length-1)
cursor_position++;
}
break;
/* move cursor left one place and delete character under cursor */
/* if k==0x0008 (backspace key) */
case 0x0008:
if (position_within_text==0) break;
position_within_text--;
if (cursor_position>0) cursor_position--;
/* fall through to next case */
/* delete character under cursor if k==0x5300 (Del key) */
case 0x5300:
if (text[position_within_text]!=0)
strcpy(text+position_within_text, text+position_within_text+1);
break;
/* insert new character to left of character under cursor */
default:
if (' '<=k && k<='~' && strlen(text)<text_length) {
char *t = text+position_within_text;
do {
int temp = *t;
*t++ = k;
k = temp;
} while (k!=0);
*t = 0;
position_within_text++;
if (cursor_position<display_length-1)
cursor_position++;
}
}
/* redisplay entire line */
{
int hidden_characters_at_left =
position_within_text-cursor_position;
char *t = text+hidden_characters_at_left;
int i;
/* display arrows at left end if necessary */
screen[-1] = hidden_characters_at_left!=0 ? 0x0FAE : 0x0700|' ';
/* display text and trailing spaces, if any */
/* use reverse video to mark cursor position */
for (i=0; i<display_length; i++) {
int c;
screen[i] = (i==cursor_position && !finished ? 0x7000 : 0x0700) |
(*t==0 ? ' ' : (c = *t++)==' ' ? 0xFA : c);
}
/* display arrows at right end if necessary */
screen[i] = *t!=0 ? 0x0FAF : 0x0700|' ';
}
if (finished) return k;
k = key();
}
}
/* test program */
void main(int argc, char **argv) {
char text[40];
int k;
int far *screen =
(int far *) ((biosequip()&0x30)==0x30 ? 0xB0000000L : 0xB8000000L);
strcpy(text, argc>1 ? argv[1] : "");
k = line_input(screen+12*80+2, text, sizeof(text)-1, 20);
printf("\nreturn value=%04X text=\"%s\"\n", k, text);
}