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 #include <debug.h>
  13
  14 NTSTATUS
  15 InitializeCircularBuffer(
  16         IN PCIRCULAR_BUFFER pBuffer,
  17         IN ULONG BufferSize)
  18 {
  19         TRACE_(SERIAL, "InitializeCircularBuffer(pBuffer %p, BufferSize %lu)\n", pBuffer, BufferSize);
  20         ASSERT(pBuffer);
  21         pBuffer->Buffer = (PUCHAR)ExAllocatePoolWithTag(NonPagedPool, BufferSize * sizeof(UCHAR), SERIAL_TAG);
  22         if (!pBuffer->Buffer)
  23                 return STATUS_INSUFFICIENT_RESOURCES;
  24         pBuffer->Length = BufferSize;
  25         pBuffer->ReadPosition = pBuffer->WritePosition = 0;
  26         return STATUS_SUCCESS;
  27 }
  28
  29 NTSTATUS
  30 FreeCircularBuffer(
  31         IN PCIRCULAR_BUFFER pBuffer)
  32 {
  33         TRACE_(SERIAL, "FreeCircularBuffer(pBuffer %p)\n", pBuffer);
  34         ASSERT(pBuffer);
  35         if (pBuffer->Buffer != NULL)
  36                 ExFreePoolWithTag(pBuffer->Buffer, SERIAL_TAG);
  37         return STATUS_SUCCESS;
  38 }
  39
  40 BOOLEAN
  41 IsCircularBufferEmpty(
  42         IN PCIRCULAR_BUFFER pBuffer)
  43 {
  44         TRACE_(SERIAL, "IsCircularBufferEmpty(pBuffer %p)\n", pBuffer);
  45         ASSERT(pBuffer);
  46         return (pBuffer->ReadPosition == pBuffer->WritePosition);
  47 }
  48
  49 ULONG
  50 GetNumberOfElementsInCircularBuffer(
  51         IN PCIRCULAR_BUFFER pBuffer)
  52 {
  53         TRACE_(SERIAL, "GetNumberOfElementsInCircularBuffer(pBuffer %p)\n", pBuffer);
  54         ASSERT(pBuffer);
  55         return (pBuffer->WritePosition + pBuffer->Length - pBuffer->ReadPosition) % pBuffer->Length;
  56 }
  57
  58 NTSTATUS
  59 PushCircularBufferEntry(
  60         IN PCIRCULAR_BUFFER pBuffer,
  61         IN UCHAR Entry)
  62 {
  63         ULONG NextPosition;
  64         TRACE_(SERIAL, "PushCircularBufferEntry(pBuffer %p, Entry 0x%x)\n", pBuffer, Entry);
  65         ASSERT(pBuffer);
  66         ASSERT(pBuffer->Length);
  67         NextPosition = (pBuffer->WritePosition + 1) % pBuffer->Length;
  68         if (NextPosition == pBuffer->ReadPosition)
  69                 return STATUS_BUFFER_TOO_SMALL;
  70         pBuffer->Buffer[pBuffer->WritePosition] = Entry;
  71         pBuffer->WritePosition = NextPosition;
  72         return STATUS_SUCCESS;
  73 }
  74
  75 NTSTATUS
  76 PopCircularBufferEntry(
  77         IN PCIRCULAR_BUFFER pBuffer,
  78         OUT PUCHAR Entry)
  79 {
  80         TRACE_(SERIAL, "PopCircularBufferEntry(pBuffer %p)\n", pBuffer);
  81         ASSERT(pBuffer);
  82         ASSERT(pBuffer->Length);
  83         if (IsCircularBufferEmpty(pBuffer))
  84                 return STATUS_ARRAY_BOUNDS_EXCEEDED;
  85         *Entry = pBuffer->Buffer[pBuffer->ReadPosition];
  86         pBuffer->ReadPosition = (pBuffer->ReadPosition + 1) % pBuffer->Length;
  87         return STATUS_SUCCESS;
  88 }
  89
  90 NTSTATUS
  91 IncreaseCircularBufferSize(
  92         IN PCIRCULAR_BUFFER pBuffer,
  93         IN ULONG NewBufferSize)
  94 {
  95         PUCHAR NewBuffer;
  96
  97         TRACE_(SERIAL, "IncreaseCircularBufferSize(pBuffer %p, NewBufferSize %lu)\n", pBuffer, NewBufferSize);
  98         ASSERT(pBuffer);
  99         ASSERT(pBuffer->Length);
 100         if (pBuffer->Length > NewBufferSize)
 101                 return STATUS_INVALID_PARAMETER;
 102         else if (pBuffer->Length == NewBufferSize)
 103                 return STATUS_SUCCESS;
 104
 105         NewBuffer = (PUCHAR)ExAllocatePoolWithTag(NonPagedPool, NewBufferSize * sizeof(UCHAR), SERIAL_TAG);
 106         if (!NewBuffer)
 107                 return STATUS_INSUFFICIENT_RESOURCES;
 108         RtlCopyMemory(NewBuffer, pBuffer->Buffer, pBuffer->Length * sizeof(UCHAR));
 109         ExFreePoolWithTag(pBuffer->Buffer, SERIAL_TAG);
 110         pBuffer->Buffer = NewBuffer;
 111         pBuffer->Length = NewBufferSize;
 112         return STATUS_SUCCESS;
 113 }