drivers/base/kdcom/kdserial.c

   1 /*
   2  * COPYRIGHT:       GPL, see COPYING in the top level directory
   3  * PROJECT:         ReactOS kernel
   4  * FILE:            drivers/base/kddll/kdserial.c
   5  * PURPOSE:         Serial communication functions for the kernel debugger.
   6  * PROGRAMMER:      Timo Kreuzer (timo.kreuzer@reactos.org)
   7  */
   8
   9 #include "kddll.h"
  10
  11 /* FUNCTIONS ******************************************************************/
  12
  13 /******************************************************************************
  14  * \name KdpSendBuffer
  15  * \brief Sends a buffer of data to the serial KD port.
  16  * \param Buffer Pointer to the data.
  17  * \param Size Size of data in bytes.
  18  */
  19 VOID
  20 NTAPI
  21 KdpSendBuffer(
  22     IN PVOID Buffer,
  23     IN ULONG Size)
  24 {
  25     PUCHAR ByteBuffer = Buffer;
  26
  27     while (Size-- > 0)
  28     {
  29         KdpSendByte(*ByteBuffer++);
  30     }
  31 }
  32
  33 /******************************************************************************
  34  * \name KdpReceiveBuffer
  35  * \brief Receives data from the KD port and fills a buffer.
  36  * \param Buffer Pointer to a buffer that receives the data.
  37  * \param Size Size of data to receive in bytes.
  38  * \return KDP_PACKET_RECEIVED if successful.
  39  *         KDP_PACKET_TIMEOUT if the receive timed out.
  40  */
  41 KDP_STATUS
  42 NTAPI
  43 KdpReceiveBuffer(
  44     OUT PVOID Buffer,
  45     IN  ULONG Size)
  46 {
  47     PUCHAR ByteBuffer = Buffer;
  48     UCHAR Byte;
  49     KDP_STATUS Status;
  50
  51     while (Size-- > 0)
  52     {
  53         /* Try to get a byte from the port */
  54         Status = KdpReceiveByte(&Byte);
  55         if (Status != KDP_PACKET_RECEIVED)
  56             return Status;
  57
  58         *ByteBuffer++ = Byte;
  59     }
  60
  61     return KDP_PACKET_RECEIVED;
  62 }
  63
  64
  65 /******************************************************************************
  66  * \name KdpReceivePacketLeader
  67  * \brief Receives a packet leader from the KD port.
  68  * \param PacketLeader Pointer to an ULONG that receives the packet leader.
  69  * \return KDP_PACKET_RECEIVED if successful.
  70  *         KDP_PACKET_TIMEOUT if the receive timed out.
  71  *         KDP_PACKET_RESEND if a breakin byte was detected.
  72  */
  73 KDP_STATUS
  74 NTAPI
  75 KdpReceivePacketLeader(
  76     OUT PULONG PacketLeader)
  77 {
  78     UCHAR Index = 0, Byte, Buffer[4];
  79     KDP_STATUS KdStatus;
  80
  81     /* Set first character to 0 */
  82     Buffer[0] = 0;
  83
  84     do
  85     {
  86         /* Receive a single byte */
  87         KdStatus = KdpReceiveByte(&Byte);
  88
  89         /* Check for timeout */
  90         if (KdStatus == KDP_PACKET_TIMEOUT)
  91         {
  92             /* Check if we already got a breakin byte */
  93             if (Buffer[0] == BREAKIN_PACKET_BYTE)
  94             {
  95                 return KDP_PACKET_RESEND;
  96             }
  97
  98             /* Report timeout */
  99             return KDP_PACKET_TIMEOUT;
 100         }
 101
 102         /* Check if we received a byte */
 103         if (KdStatus == KDP_PACKET_RECEIVED)
 104         {
 105             /* Check if this is a valid packet leader byte */
 106             if (Byte == PACKET_LEADER_BYTE ||
 107                 Byte == CONTROL_PACKET_LEADER_BYTE)
 108             {
 109                 /* Check if we match the first byte */
 110                 if (Byte != Buffer[0])
 111                 {
 112                     /* No, this is the new byte 0! */
 113                     Index = 0;
 114                 }
 115
 116                 /* Store the byte in the buffer */
 117                 Buffer[Index] = Byte;
 118
 119                 /* Continue with next byte */
 120                 Index++;
 121                 continue;
 122             }
 123
 124             /* Check for breakin byte */
 125             if (Byte == BREAKIN_PACKET_BYTE)
 126             {
 127                 KDDBGPRINT("BREAKIN_PACKET_BYTE\n");
 128                 Index = 0;
 129                 Buffer[0] = Byte;
 130                 continue;
 131             }
 132         }
 133
 134         /* Restart */
 135         Index = 0;
 136         Buffer[0] = 0;
 137     }
 138     while (Index < 4);
 139
 140     /* Enable the debugger */
 141     KD_DEBUGGER_NOT_PRESENT = FALSE;
 142     SharedUserData->KdDebuggerEnabled |= 0x00000002;
 143
 144     /* Return the received packet leader */
 145     *PacketLeader = *(PULONG)Buffer;
 146
 147     return KDP_PACKET_RECEIVED;
 148 }
 149
 150 /* EOF */