osfmk/kdp/kdp_serial.c

   1 /*
   2  * Copyright (c) 2008 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 #include "kdp_serial.h"
  29
  30 #define SKDP_START_CHAR 0xFA
  31 #define SKDP_END_CHAR 0xFB
  32 #define SKDP_ESC_CHAR 0xFE
  33
  34 static enum {DS_WAITSTART, DS_READING, DS_ESCAPED} dsState;
  35 static unsigned char dsBuffer[1518];
  36 static int dsPos;
  37
  38 void kdp_serialize_packet(unsigned char *packet, unsigned int len, void (*outFunc)(char))
  39 {
  40         unsigned int index;
  41         outFunc(SKDP_START_CHAR);
  42         for (index = 0; index < len; index++) {
  43                 unsigned char byte = *packet++;
  44                 //need to escape '\n' because the kernel serial output turns it into a cr/lf
  45                 if(byte == SKDP_START_CHAR || byte == SKDP_END_CHAR || byte == SKDP_ESC_CHAR || byte == '\n')
  46                 {
  47                         outFunc(SKDP_ESC_CHAR);
  48                         byte = ~byte;
  49                 }
  50                 outFunc(byte);
  51         }
  52         outFunc(SKDP_END_CHAR);
  53 }
  54
  55 unsigned char *kdp_unserialize_packet(unsigned char byte, unsigned int *len)
  56 {
  57         switch(dsState)
  58         {
  59                 case DS_WAITSTART:
  60                         if(byte == SKDP_START_CHAR)
  61                         {
  62 //                              printf("got start char\n");
  63                                 dsState = DS_READING;
  64                                 dsPos = 0;
  65                                 *len = SERIALIZE_READING;
  66                                 return 0;
  67                         }
  68                         *len = SERIALIZE_WAIT_START;
  69                         break;
  70                 case DS_READING:
  71                         if(byte == SKDP_ESC_CHAR)
  72                         {
  73                                 dsState = DS_ESCAPED;
  74                                 *len = SERIALIZE_READING;
  75                                 return 0;
  76                         }
  77                         if(byte == SKDP_START_CHAR)
  78                         {
  79 //                              printf("unexpected start char, resetting\n");
  80                                 dsPos = 0;
  81                                 *len = SERIALIZE_READING;
  82                                 return 0;
  83                         }
  84                         if(byte == SKDP_END_CHAR)
  85                         {
  86                                 dsState = DS_WAITSTART;
  87                                 *len = dsPos;
  88                                 dsPos = 0;
  89                                 return dsBuffer;
  90                         }
  91                         dsBuffer[dsPos++] = byte;
  92                         break;
  93                 case DS_ESCAPED:
  94 //                      printf("unescaping %02x to %02x\n", byte, ~byte);
  95                         dsBuffer[dsPos++] = ~byte;
  96                         dsState = DS_READING;
  97                         *len = SERIALIZE_READING;
  98                         break;
  99         }
 100         if(dsPos == sizeof(dsBuffer)) //too much data...forget this packet
 101         {
 102                 dsState = DS_WAITSTART;
 103                 dsPos = 0;
 104                 *len = SERIALIZE_WAIT_START;
 105         }
 106
 107         return 0;
 108 }