{ USB serial port wrapper services for Mikropascal PIC32 }

{ Copyright (C)2015-2018, Philip Munts, President, Munts AM Corp.             }
{                                                                             }
{ Redistribution and use in source and binary forms, with or without          }
{ modification, are permitted provided that the following conditions are met: }
{                                                                             }
{ * Redistributions of source code must retain the above copyright notice,    }
{   this list of conditions and the following disclaimer.                     }
{                                                                             }
{ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" }
{ AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE   }
{ IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE  }
{ ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE   }
{ LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR         }
{ CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF        }
{ SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS    }
{ INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN     }
{ CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)     }
{ ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE  }
{ POSSIBILITY OF SUCH DAMAGE.                                                 }

UNIT usb_serial;

  PROCEDURE USB_Serial_Init();

  FUNCTION USB_Serial_Data_Ready() : boolean;

  FUNCTION USB_Serial_Read() : byte;

  FUNCTION USB_Serial_Tx_Idle() : boolean;

  PROCEDURE USB_Serial_Write(c : byte);

  PROCEDURE USB_Serial_Write_Text(VAR s : string);

  PROCEDURE USBDev_CDCParamsChanged();

  PROCEDURE USBDev_CDCDataReceived(size : word);

  PROCEDURE USBDev_CDCDataSent(ep : byte);

IMPLEMENTATION

  CONST
    QUEUE_SIZE = 256;

  VAR
    ReceiveBuffer : ARRAY [1 .. 64] OF byte;
    ReceiveQueue : ARRAY [0 .. QUEUE_SIZE-1] OF byte;
    head : integer;
    tail : integer;
    count : integer;
    sending : boolean;

  PROCEDURE USB_Serial_Init();

  BEGIN
    head := 0;
    tail := 0;
    count := 0;
    sending := false;

    { Initialize the USB subsystem }

    USBDev_CDCInit();
    USBDev_Init();
    USBDev_RegisterDataSentHandler(@USBDev_CDCDataSent);

    USBIE_bit := 1;
    IPC11 := dword(7) shl USBIP0;
    EnableInterrupts();

    { Wait until we have been enumerated by the USB host }

    REPEAT
    UNTIL USBDev_GetDeviceState() = _USB_DEV_STATE_CONFIGURED;

    USBDev_CDCSetReceiveBuffer(@ReceiveBuffer);
  END;

  FUNCTION USB_Serial_Data_Ready() : boolean;

  BEGIN
    IF count > 0 THEN
      USB_Serial_Data_Ready := true
    ELSE
      USB_Serial_Data_Ready := false;
  END;

  FUNCTION USB_Serial_Read() : byte;

  BEGIN
    REPEAT
    UNTIL count > 0;

    USB_Serial_Read := ReceiveQueue[head];
    DisableInterrupts();
    dec(count);
    EnableInterrupts();

    inc(head);
    IF head = QUEUE_SIZE THEN
      head := 0;
  END;

  FUNCTION USB_Serial_Tx_Idle() : boolean;

  BEGIN
    USB_Serial_Tx_Idle := NOT sending;
  END;

  PROCEDURE USB_Serial_Write(c : byte);

  BEGIN
    REPEAT
    UNTIL NOT sending;

    sending := true;
    USBDev_CDCSendData(@c, 1);
    delay_ms(1);
  END;

  PROCEDURE USB_Serial_Write_Text(VAR s : string);

  BEGIN
    REPEAT
    UNTIL NOT sending;

    sending := true;
    USBDev_CDCSendData(@s, strlen(s));
    delay_ms(1);
  END;

  FUNCTION Min(x, y : integer) : integer;

  BEGIN
    IF x < y THEN
      Min := x
    ELSE
      Min := y;
  END;

  PROCEDURE USBDev_CDCParamsChanged();

  BEGIN
  END;

  PROCEDURE USBDev_CDCDataReceived(size : word);

  VAR
    i : integer;

  BEGIN
    size := Min(size, QUEUE_SIZE - count);

    FOR i := 1 TO size DO
      BEGIN
        ReceiveQueue[tail] := ReceiveBuffer[i];

        inc(tail);
        inc(count);

        IF tail = QUEUE_SIZE THEN
          tail := 0;
      END;

    USBDev_CDCSetReceiveBuffer(@ReceiveBuffer);
  END;

  PROCEDURE USBDev_CDCDataSent(ep : byte);

  BEGIN
    sending := false;
  END;

  PROCEDURE USB0Interrupt(); iv IVT_USB_1; ilevel 7; ics ICS_SRS;

  BEGIN
    USBDev_IntHandler();
  END;
END.