src/core/ansiesc.c

   1 /*
   2  * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 #include <string.h>
  20 #include <assert.h>
  21 #include <gpxe/ansiesc.h>
  22
  23 /** @file
  24  *
  25  * ANSI escape sequences
  26  *
  27  */
  28
  29 /**
  30  * Call ANSI escape sequence handler
  31  *
  32  * @v handlers          List of escape sequence handlers
  33  * @v function          Control function identifier
  34  * @v count             Parameter count
  35  * @v params            Parameter list
  36  */
  37 static void ansiesc_call_handler ( struct ansiesc_handler *handlers,
  38                                    unsigned int function, int count,
  39                                    int params[] ) {
  40         struct ansiesc_handler *handler;
  41
  42         for ( handler = handlers ; handler->function ; handler++ ) {
  43                 if ( handler->function == function ) {
  44                         handler->handle ( count, params );
  45                         break;
  46                 }
  47         }
  48 }
  49
  50 /**
  51  * Process character that may be part of ANSI escape sequence
  52  *
  53  * @v ctx               ANSI escape sequence context
  54  * @v c                 Character
  55  * @ret c               Original character if not part of escape sequence
  56  * @ret <0              Character was part of escape sequence
  57  *
  58  * ANSI escape sequences will be plucked out of the character stream
  59  * and interpreted; once complete they will be passed to the
  60  * appropriate handler if one exists in this ANSI escape sequence
  61  * context.
  62  *
  63  * In the interests of code size, we are rather liberal about the
  64  * sequences we are prepared to accept as valid.
  65  */
  66 int ansiesc_process ( struct ansiesc_context *ctx, int c ) {
  67         if ( ctx->count == 0 ) {
  68                 if ( c == ESC ) {
  69                         /* First byte of CSI : begin escape sequence */
  70                         ctx->count = 1;
  71                         memset ( ctx->params, 0xff, sizeof ( ctx->params ) );
  72                         ctx->function = 0;
  73                         return -1;
  74                 } else {
  75                         /* Normal character */
  76                         return c;
  77                 }
  78         } else {
  79                 if ( c == '[' ) {
  80                         /* Second byte of CSI : do nothing */
  81                 } else if ( ( c >= '0' ) && ( c <= '9' ) ) {
  82                         /* Parameter Byte : part of a parameter value */
  83                         int *param = &ctx->params[ctx->count - 1];
  84                         if ( *param < 0 )
  85                                 *param = 0;
  86                         *param = ( ( *param * 10 ) + ( c - '0' ) );
  87                 } else if ( c == ';' ) {
  88                         /* Parameter Byte : parameter delimiter */
  89                         ctx->count++;
  90                         if ( ctx->count > ( sizeof ( ctx->params ) /
  91                                             sizeof ( ctx->params[0] ) ) ) {
  92                                 /* Excessive parameters : abort sequence */
  93                                 ctx->count = 0;
  94                                 DBG ( "Too many parameters in ANSI escape "
  95                                       "sequence\n" );
  96                         }
  97                 } else if ( ( c >= 0x20 ) && ( c <= 0x2f ) ) {
  98                         /* Intermediate Byte */
  99                         ctx->function <<= 8;
 100                         ctx->function |= c;
 101                 } else {
 102                         /* Treat as Final Byte.  Zero ctx->count before
 103                          * calling handler to avoid potential infinite loops.
 104                          */
 105                         int count = ctx->count;
 106                         ctx->count = 0;
 107                         ctx->function <<= 8;
 108                         ctx->function |= c;
 109                         ansiesc_call_handler ( ctx->handlers, ctx->function,
 110                                                count, ctx->params );
 111                 }
 112                 return -1;
 113         }
 114 }