110 lines
3.4 KiB
C
110 lines
3.4 KiB
C
/* Created: 2025-06-15 Russell-S-Harper
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** Modified: <iso-date> <author>
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** Notes: <e.g. revisions made to support target, edge cases, bugs, etc.>
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**
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** char *cgets(char *buffer);
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*/
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#include <stddef.h>
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#include <conio.h>
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#include <string.h>
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#include <ctype.h>
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enum {CGETS_SIZE, CGETS_READ, CGETS_DATA, CGETS_HDR_LEN = CGETS_DATA};
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static char *cgetsx (char *buffer, int size);
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char *cgets (char *buffer)
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/* Get a string of characters directly from the console. The standard interface
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** is quirky:
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**
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** - set buffer[0] to the size of the buffer - 2, must be > 0
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** - call cgets
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** - buffer[1] will have the number of characters read
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** - the actual string starts at buffer + 2
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** - terminating \0 is appended
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** - therefore the maximum number of characters which can be read is the size
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** of the buffer - 3!
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** - note: CR/LF are NOT echoed, typically a following call to cputs or
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** cprintf will need "\r\n" prepended - this is standard behavior!
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**
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** param: buffer - where to save the input
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** return: buffer + 2 (i.e. start of the string) or NULL if buffer is NULL
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*/
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{
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/* Return buffer + 2 or NULL if buffer is NULL */
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char *result = buffer? buffer + CGETS_HDR_LEN: NULL;
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if (result) {
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/* Initialize just in case the caller didn't! */
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buffer[CGETS_READ] = 0;
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buffer[CGETS_DATA] = '\0';
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/* Call cgetsx to do the real work, ignore the result! */
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cgetsx (result, (unsigned char)buffer[CGETS_SIZE]);
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/* Set how many characters were read */
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buffer[CGETS_READ] = (unsigned char)strlen (result);
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}
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/* Done */
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return result;
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}
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static char *cgetsx (char *buffer, int size)
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/* Like fgets but specifically for the console. Stops when CR/LF or size - 1
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** characters are read. Will append a terminating \0, so at most size - 1
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** characters can be read. Note that this function could be made public and
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** have features added like cursor vs no-cursor, echo vs echo-pwd vs no-echo,
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** or CR/LF handling to extend the functionality.
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**
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** param: buffer - where to save the input
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** param: size - the size of buffer
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** return: buffer if successful, NULL otherwise
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*/
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{
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int i = 0;
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unsigned char w, x, y;
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char c;
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if (buffer && size > 1) {
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/* Just need the width */
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screensize (&w, &y);
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/* Actually just the last column! */
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--w;
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cursor (1);
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for (i = 0, --size; i < size; ) {
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c = cgetc ();
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/* Handle backspace */
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if (c == '\b') {
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if (i > 0) {
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/* Remove the character */
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buffer[--i] = '\0';
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/* Logic to account for line wrapping */
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y = wherey ();
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x = wherex ();
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y = x? y: y - 1;
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x = x? x - 1: w;
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/* Clear the character */
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gotoxy (x, y);
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cputc (' ');
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gotoxy (x, y);
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}
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/* Handle regular characters */
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} else if (isprint (c)) {
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cputc (c);
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buffer[i] = c;
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buffer[++i] = '\0';
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/* Handle CR/LF */
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} else if (c == '\r' || c == '\n') {
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buffer[i] = '\0';
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break;
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}
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}
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cursor (0);
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}
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/* Done */
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return (i > 0)? buffer: NULL;
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}
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