drivers/serial/serial/circularbuffer.c

   1 /*
   2  * COPYRIGHT:       See COPYING in the top level directory
   3  * PROJECT:         Serial port driver
   4  * FILE:            drivers/dd/serial/circularbuffer.c
   5  * PURPOSE:         Operations on a circular buffer
   6  *
   7  * PROGRAMMERS:     Hervé Poussineau (hpoussin@reactos.org)
   8  */
   9
  10 #include "serial.h"
  11
  12 NTSTATUS
  13 InitializeCircularBuffer(
  14         IN PCIRCULAR_BUFFER pBuffer,
  15         IN ULONG BufferSize)
  16 {
  17         TRACE_(SERIAL, "InitializeCircularBuffer(pBuffer %p, BufferSize %lu)\n", pBuffer, BufferSize);
  18         ASSERT(pBuffer);
  19         pBuffer->Buffer = (PUCHAR)ExAllocatePoolWithTag(NonPagedPool, BufferSize * sizeof(UCHAR), SERIAL_TAG);
  20         if (!pBuffer->Buffer)
  21                 return STATUS_INSUFFICIENT_RESOURCES;
  22         pBuffer->Length = BufferSize;
  23         pBuffer->ReadPosition = pBuffer->WritePosition = 0;
  24         return STATUS_SUCCESS;
  25 }
  26
  27 NTSTATUS
  28 FreeCircularBuffer(
  29         IN PCIRCULAR_BUFFER pBuffer)
  30 {
  31         TRACE_(SERIAL, "FreeCircularBuffer(pBuffer %p)\n", pBuffer);
  32         ASSERT(pBuffer);
  33         if (pBuffer->Buffer != NULL)
  34                 ExFreePoolWithTag(pBuffer->Buffer, SERIAL_TAG);
  35         return STATUS_SUCCESS;
  36 }
  37
  38 BOOLEAN
  39 IsCircularBufferEmpty(
  40         IN PCIRCULAR_BUFFER pBuffer)
  41 {
  42         TRACE_(SERIAL, "IsCircularBufferEmpty(pBuffer %p)\n", pBuffer);
  43         ASSERT(pBuffer);
  44         return (pBuffer->ReadPosition == pBuffer->WritePosition);
  45 }
  46
  47 ULONG
  48 GetNumberOfElementsInCircularBuffer(
  49         IN PCIRCULAR_BUFFER pBuffer)
  50 {
  51         TRACE_(SERIAL, "GetNumberOfElementsInCircularBuffer(pBuffer %p)\n", pBuffer);
  52         ASSERT(pBuffer);
  53         return (pBuffer->WritePosition + pBuffer->Length - pBuffer->ReadPosition) % pBuffer->Length;
  54 }
  55
  56 NTSTATUS
  57 PushCircularBufferEntry(
  58         IN PCIRCULAR_BUFFER pBuffer,
  59         IN UCHAR Entry)
  60 {
  61         ULONG NextPosition;
  62         TRACE_(SERIAL, "PushCircularBufferEntry(pBuffer %p, Entry 0x%x)\n", pBuffer, Entry);
  63         ASSERT(pBuffer);
  64         ASSERT(pBuffer->Length);
  65         NextPosition = (pBuffer->WritePosition + 1) % pBuffer->Length;
  66         if (NextPosition == pBuffer->ReadPosition)
  67                 return STATUS_BUFFER_TOO_SMALL;
  68         pBuffer->Buffer[pBuffer->WritePosition] = Entry;
  69         pBuffer->WritePosition = NextPosition;
  70         return STATUS_SUCCESS;
  71 }
  72
  73 NTSTATUS
  74 PopCircularBufferEntry(
  75         IN PCIRCULAR_BUFFER pBuffer,
  76         OUT PUCHAR Entry)
  77 {
  78         TRACE_(SERIAL, "PopCircularBufferEntry(pBuffer %p)\n", pBuffer);
  79         ASSERT(pBuffer);
  80         ASSERT(pBuffer->Length);
  81         if (IsCircularBufferEmpty(pBuffer))
  82                 return STATUS_ARRAY_BOUNDS_EXCEEDED;
  83         *Entry = pBuffer->Buffer[pBuffer->ReadPosition];
  84         pBuffer->ReadPosition = (pBuffer->ReadPosition + 1) % pBuffer->Length;
  85         return STATUS_SUCCESS;
  86 }
  87
  88 NTSTATUS
  89 IncreaseCircularBufferSize(
  90         IN PCIRCULAR_BUFFER pBuffer,
  91         IN ULONG NewBufferSize)
  92 {
  93         PUCHAR NewBuffer;
  94
  95         TRACE_(SERIAL, "IncreaseCircularBufferSize(pBuffer %p, NewBufferSize %lu)\n", pBuffer, NewBufferSize);
  96         ASSERT(pBuffer);
  97         ASSERT(pBuffer->Length);
  98         if (pBuffer->Length > NewBufferSize)
  99                 return STATUS_INVALID_PARAMETER;
 100         else if (pBuffer->Length == NewBufferSize)
 101                 return STATUS_SUCCESS;
 102
 103         NewBuffer = (PUCHAR)ExAllocatePoolWithTag(NonPagedPool, NewBufferSize * sizeof(UCHAR), SERIAL_TAG);
 104         if (!NewBuffer)
 105                 return STATUS_INSUFFICIENT_RESOURCES;
 106         RtlCopyMemory(NewBuffer, pBuffer->Buffer, pBuffer->Length * sizeof(UCHAR));
 107         ExFreePoolWithTag(pBuffer->Buffer, SERIAL_TAG);
 108         pBuffer->Buffer = NewBuffer;
 109         pBuffer->Length = NewBufferSize;
 110         return STATUS_SUCCESS;
 111 }