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heap.c
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heap.c
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/* Copyright (C) 2013 by John Cronin <jncronin@tysos.org>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <stdint.h>
#include <stdio.h>
#define MAX_BRK (((uintptr_t)&_start - 0x8000) + 0xf0000)
#ifdef ENABLE_USB
#include "dwc_usb.h"
#define MAX_BUF DWC_USB_FIFO_START
#else
#define MAX_BUF 0x100000
#endif
extern char _start, _end;
uintptr_t cur_brk = 0;
uintptr_t cur_buf = MAX_BRK;
uintptr_t alloc_buf(size_t size)
{
uintptr_t old_buf = cur_buf;
cur_buf += size;
if(cur_buf > MAX_BUF)
{
cur_buf = old_buf;
return 0;
}
// Align up to a 512 byte value
if(cur_buf & 0x1ff)
{
cur_buf &= ~0x1ff;
cur_buf += 0x200;
}
return old_buf;
}
void *sbrk(uint32_t increment)
{
// sbrk returns the previous brk value
// First set up cur_brk if not done already
if(cur_brk == 0)
{
#ifdef DEBUG2
printf("HEAP: initializing at %p\n", &_end);
#endif
cur_brk = (uintptr_t)&_end;
if(cur_brk & 0xfff)
{
cur_brk &= 0xfffff000;
cur_brk += 0x1000;
}
}
uintptr_t old_brk = cur_brk;
cur_brk += increment;
if(cur_brk >= MAX_BRK)
{
cur_brk = old_brk;
return (void*)-1;
}
return (void*)old_brk;
}