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//
// TPCircularBuffer.c
// Circular/Ring buffer implementation
//
// https://github.com/michaeltyson/TPCircularBuffer
//
// Created by Michael Tyson on 10/12/2011.
//
// Copyright (C) 2012-2013 A Tasty Pixel
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software. If you use this software
// in a product, an acknowledgment in the product documentation would be
// appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not be
// misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source distribution.
//
#include <winpr/wlog.h>
#include "TPCircularBuffer.h"
#include "rdpsnd_main.h"
#include <mach/mach.h>
#include <stdio.h>
#define reportResult(result, operation) (_reportResult((result), (operation), __FILE__, __LINE__))
static inline bool _reportResult(kern_return_t result, const char* operation, const char* file,
int line)
{
if (result != ERR_SUCCESS)
{
WLog_DBG(TAG, "%s:%d: %s: %s\n", file, line, operation, mach_error_string(result));
return false;
}
return true;
}
bool TPCircularBufferInit(TPCircularBuffer* buffer, int length)
{
// Keep trying until we get our buffer, needed to handle race conditions
int retries = 3;
while (true)
{
buffer->length = round_page(length); // We need whole page sizes
// Temporarily allocate twice the length, so we have the contiguous address space to
// support a second instance of the buffer directly after
vm_address_t bufferAddress;
kern_return_t result = vm_allocate(mach_task_self(), &bufferAddress, buffer->length * 2,
VM_FLAGS_ANYWHERE); // allocate anywhere it'll fit
if (result != ERR_SUCCESS)
{
if (retries-- == 0)
{
reportResult(result, "Buffer allocation");
return false;
}
// Try again if we fail
continue;
}
// Now replace the second half of the allocation with a virtual copy of the first half.
// Deallocate the second half...
result = vm_deallocate(mach_task_self(), bufferAddress + buffer->length, buffer->length);
if (result != ERR_SUCCESS)
{
if (retries-- == 0)
{
reportResult(result, "Buffer deallocation");
return false;
}
// If this fails somehow, deallocate the whole region and try again
vm_deallocate(mach_task_self(), bufferAddress, buffer->length);
continue;
}
// Re-map the buffer to the address space immediately after the buffer
vm_address_t virtualAddress = bufferAddress + buffer->length;
vm_prot_t cur_prot, max_prot;
result = vm_remap(mach_task_self(),
&virtualAddress, // mirror target
buffer->length, // size of mirror
0, // auto alignment
0, // force remapping to virtualAddress
mach_task_self(), // same task
bufferAddress, // mirror source
0, // MAP READ-WRITE, NOT COPY
&cur_prot, // unused protection struct
&max_prot, // unused protection struct
VM_INHERIT_DEFAULT);
if (result != ERR_SUCCESS)
{
if (retries-- == 0)
{
reportResult(result, "Remap buffer memory");
return false;
}
// If this remap failed, we hit a race condition, so deallocate and try again
vm_deallocate(mach_task_self(), bufferAddress, buffer->length);
continue;
}
if (virtualAddress != bufferAddress + buffer->length)
{
// If the memory is not contiguous, clean up both allocated buffers and try again
if (retries-- == 0)
{
WLog_DBG(TAG, "Couldn't map buffer memory to end of buffer");
return false;
}
vm_deallocate(mach_task_self(), virtualAddress, buffer->length);
vm_deallocate(mach_task_self(), bufferAddress, buffer->length);
continue;
}
buffer->buffer = (void*)bufferAddress;
buffer->fillCount = 0;
buffer->head = buffer->tail = 0;
return true;
}
return false;
}
void TPCircularBufferCleanup(TPCircularBuffer* buffer)
{
vm_deallocate(mach_task_self(), (vm_address_t)buffer->buffer, buffer->length * 2);
memset(buffer, 0, sizeof(TPCircularBuffer));
}
void TPCircularBufferClear(TPCircularBuffer* buffer)
{
int32_t fillCount;
if (TPCircularBufferTail(buffer, &fillCount))
{
TPCircularBufferConsume(buffer, fillCount);
}
}
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