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 FILE_LICENCE ( GPL2_OR_LATER );
20 
21 #include <string.h>
22 #include <assert.h>
23 #include <gpxe/ansiesc.h>
24 
25 /** @file
26  *
27  * ANSI escape sequences
28  *
29  */
30 
31 /**
32  * Call ANSI escape sequence handler
33  *
34  * @v handlers		List of escape sequence handlers
35  * @v function		Control function identifier
36  * @v count		Parameter count
37  * @v params		Parameter list
38  */
39 static void ansiesc_call_handler ( struct ansiesc_handler *handlers,
40 				   unsigned int function, int count,
41 				   int params[] ) {
42 	struct ansiesc_handler *handler;
43 
44 	for ( handler = handlers ; handler->function ; handler++ ) {
45 		if ( handler->function == function ) {
46 			handler->handle ( count, params );
47 			break;
48 		}
49 	}
50 }
51 
52 /**
53  * Process character that may be part of ANSI escape sequence
54  *
55  * @v ctx		ANSI escape sequence context
56  * @v c			Character
57  * @ret c		Original character if not part of escape sequence
58  * @ret <0		Character was part of escape sequence
59  *
60  * ANSI escape sequences will be plucked out of the character stream
61  * and interpreted; once complete they will be passed to the
62  * appropriate handler if one exists in this ANSI escape sequence
63  * context.
64  *
65  * In the interests of code size, we are rather liberal about the
66  * sequences we are prepared to accept as valid.
67  */
68 int ansiesc_process ( struct ansiesc_context *ctx, int c ) {
69 	if ( ctx->count == 0 ) {
70 		if ( c == ESC ) {
71 			/* First byte of CSI : begin escape sequence */
72 			ctx->count = 1;
73 			memset ( ctx->params, 0xff, sizeof ( ctx->params ) );
74 			ctx->function = 0;
75 			return -1;
76 		} else {
77 			/* Normal character */
78 			return c;
79 		}
80 	} else {
81 		if ( c == '[' ) {
82 			/* Second byte of CSI : do nothing */
83 		} else if ( ( c >= '0' ) && ( c <= '9' ) ) {
84 			/* Parameter Byte : part of a parameter value */
85 			int *param = &ctx->params[ctx->count - 1];
86 			if ( *param < 0 )
87 				*param = 0;
88 			*param = ( ( *param * 10 ) + ( c - '0' ) );
89 		} else if ( c == ';' ) {
90 			/* Parameter Byte : parameter delimiter */
91 			ctx->count++;
92 			if ( ctx->count > ( sizeof ( ctx->params ) /
93 					    sizeof ( ctx->params[0] ) ) ) {
94 				/* Excessive parameters : abort sequence */
95 				ctx->count = 0;
96 				DBG ( "Too many parameters in ANSI escape "
97 				      "sequence\n" );
98 			}
99 		} else if ( ( c >= 0x20 ) && ( c <= 0x2f ) ) {
100 			/* Intermediate Byte */
101 			ctx->function <<= 8;
102 			ctx->function |= c;
103 		} else {
104 			/* Treat as Final Byte.  Zero ctx->count before
105 			 * calling handler to avoid potential infinite loops.
106 			 */
107 			int count = ctx->count;
108 			ctx->count = 0;
109 			ctx->function <<= 8;
110 			ctx->function |= c;
111 			ansiesc_call_handler ( ctx->handlers, ctx->function,
112 					       count, ctx->params );
113 		}
114 		return -1;
115 	}
116 }
117