less -> more

[unix-history] / usr / src / usr.bin / more / decode.c

/*
* Copyright (c) 1988 Mark Nudleman
* Copyright (c) 1988 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by Mark Nudleman and the University of California, Berkeley.  The
* name of Mark Nudleman or the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/

#ifndef lint
static char sccsid[] = "@(#)decode.c    5.6 (Berkeley) %G%";
#endif /* not lint */

/*
* Routines to decode user commands.
*
* This is all table driven.
* A command table is a sequence of command descriptors.
* Each command descriptor is a sequence of bytes with the following format:
*      <c1><c2>...<cN><0><action>
* The characters c1,c2,...,cN are the command string; that is,
* the characters which the user must type.
* It is terminated by a null <0> byte.
* The byte after the null byte is the action code associated
* with the command string.
*
* The default commands are described by cmdtable.
*/

#include <sys/param.h>
#include <sys/file.h>
#include <stdio.h>
#include <less.h>

/*
* Command table is ordered roughly according to expected
* frequency of use, so the common commands are near the beginning.
*/
#define CONTROL(c)              ((c)&037)

static char cmdtable[] = {
       '\r',0,                         A_F_LINE,
       '\n',0,                         A_F_LINE,
       'j',0,                          A_F_LINE,
       'k',0,                          A_B_LINE,
       'd',0,                          A_F_SCROLL,
       CONTROL('D'),0,                 A_F_SCROLL,
       'u',0,                          A_B_SCROLL,
       CONTROL('U'),0,                 A_B_SCROLL,
       ' ',0,                          A_F_SCREEN,
       'f',0,                          A_F_SCREEN,
       CONTROL('F'),0,                 A_F_SCREEN,
       'b',0,                          A_B_SCREEN,
       CONTROL('B'),0,                 A_B_SCREEN,
       'R',0,                          A_FREPAINT,
       'r',0,                          A_REPAINT,
       CONTROL('L'),0,                 A_REPAINT,
       'g',0,                          A_GOLINE,
       'p',0,                          A_PERCENT,
       '%',0,                          A_PERCENT,
       'G',0,                          A_GOEND,
       '0',0,                          A_DIGIT,
       '1',0,                          A_DIGIT,
       '2',0,                          A_DIGIT,
       '3',0,                          A_DIGIT,
       '4',0,                          A_DIGIT,
       '5',0,                          A_DIGIT,
       '6',0,                          A_DIGIT,
       '7',0,                          A_DIGIT,
       '8',0,                          A_DIGIT,
       '9',0,                          A_DIGIT,

       '=',0,                          A_STAT,
       CONTROL('G'),0,                 A_STAT,
       '/',0,                          A_F_SEARCH,
       '?',0,                          A_B_SEARCH,
       'n',0,                          A_AGAIN_SEARCH,
       'm',0,                          A_SETMARK,
       '\'',0,                         A_GOMARK,
       'E',0,                          A_EXAMINE,
       'N',0,                          A_NEXT_FILE,
       ':','n',0,                      A_NEXT_FILE,
       'P',0,                          A_PREV_FILE,
       ':','p',0,                      A_PREV_FILE,
       'v',0,                          A_VISUAL,

       'h',0,                          A_HELP,
       'q',0,                          A_QUIT,
       ':','q',0,                      A_QUIT,
       ':','t',0,                      A_TAGFILE,
       'Z','Z',0,                      A_QUIT,
};

char *cmdendtable = cmdtable + sizeof(cmdtable);

#define MAX_CMDLEN      16

static char kbuf[MAX_CMDLEN+1];
static char *kp = kbuf;

/*
* Indicate that we're not in a prefix command
* by resetting the command buffer pointer.
*/
noprefix()
{
       kp = kbuf;
}

/*
* Decode a command character and return the associated action.
*/
cmd_decode(c)
       int c;
{
       register int action = A_INVALID;

       /*
        * Append the new command character to the command string in kbuf.
        */
       *kp++ = c;
       *kp = '\0';

       action = cmd_search(cmdtable, cmdendtable);

       /* This is not a prefix character. */
       if (action != A_PREFIX)
               noprefix();
       return(action);
}

/*
* Search a command table for the current command string (in kbuf).
*/
static
cmd_search(table, endtable)
       char *table;
       char *endtable;
{
       register char *p, *q;

       for (p = table, q = kbuf;  p < endtable;  p++, q++) {
               if (*p == *q) {
                       /*
                        * Current characters match.
                        * If we're at the end of the string, we've found it.
                        * Return the action code, which is the character
                        * after the null at the end of the string
                        * in the command table.
                        */
                       if (*p == '\0')
                               return(p[1]);
               }
               else if (*q == '\0') {
                       /*
                        * Hit the end of the user's command,
                        * but not the end of the string in the command table.
                        * The user's command is incomplete.
                        */
                       return(A_PREFIX);
               } else {
                       /*
                        * Not a match.
                        * Skip ahead to the next command in the
                        * command table, and reset the pointer
                        * to the user's command.
                        */
                       while (*p++ != '\0');
                       q = kbuf-1;
               }
       }
       /*
        * No match found in the entire command table.
        */
       return(A_INVALID);
}