SerialPortLib.c

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#include <Uefi.h>
#include <Library/DebugLib.h>
#include <Library/SemihostLib.h>
#include <Library/SerialPortLib.h>
 
/*
 
  Programmed hardware of Serial port.
 
  @return    Always return EFI_UNSUPPORTED.
 
**/
RETURN_STATUS
EFIAPI
SerialPortInitialize (
  VOID
  )
{
  if (SemihostConnectionSupported ()) {
    return RETURN_SUCCESS;
  } else {
    return RETURN_UNSUPPORTED;
  }
}
 
#define PRINT_BUFFER_SIZE       512
#define PRINT_BUFFER_THRESHOLD  (PRINT_BUFFER_SIZE - 4)
 
UINTN
EFIAPI
SerialPortWrite (
  IN UINT8  *Buffer,
  IN UINTN  NumberOfBytes
  )
{
  UINT8  PrintBuffer[PRINT_BUFFER_SIZE];
  UINTN  SourceIndex;
  UINTN  DestinationIndex;
  UINT8  CurrentCharacter;
 
  SourceIndex      = 0;
  DestinationIndex = 0;
 
  while (SourceIndex < NumberOfBytes) {
    CurrentCharacter = Buffer[SourceIndex++];
 
    switch (CurrentCharacter) {
      case '\r':
        continue;
 
      case '\n':
        PrintBuffer[DestinationIndex++] = ' ';
      // fall through
 
      default:
        PrintBuffer[DestinationIndex++] = CurrentCharacter;
        break;
    }
 
    if (DestinationIndex > PRINT_BUFFER_THRESHOLD) {
      PrintBuffer[DestinationIndex] = '\0';
      SemihostWriteString ((CHAR8 *)PrintBuffer);
 
      DestinationIndex = 0;
    }
  }
 
  if (DestinationIndex > 0) {
    PrintBuffer[DestinationIndex] = '\0';
    SemihostWriteString ((CHAR8 *)PrintBuffer);
  }
 
  return NumberOfBytes;
}
 
UINTN
EFIAPI
SerialPortRead (
  OUT UINT8  *Buffer,
  IN  UINTN  NumberOfBytes
  )
{
  *Buffer = SemihostReadCharacter ();
  return 1;
}
 
BOOLEAN
EFIAPI
SerialPortPoll (
  VOID
  )
{
  // Since SemiHosting read character is blocking always say we have a char ready?
  return SemihostConnectionSupported ();
}