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circuitpython/supervisor/shared/memory.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2018 Scott Shawcroft for Adafruit Industries
*
* 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 "supervisor/memory.h"
#include <stddef.h>
#include "supervisor/shared/display.h"
#define CIRCUITPY_SUPERVISOR_ALLOC_COUNT 8
static supervisor_allocation allocations[CIRCUITPY_SUPERVISOR_ALLOC_COUNT];
// We use uint32_t* to ensure word (4 byte) alignment.
uint32_t* low_address;
uint32_t* high_address;
extern uint32_t _ebss;
extern uint32_t _estack;
void memory_init(void) {
low_address = &_ebss;
high_address = &_estack;
}
void free_memory(supervisor_allocation* allocation) {
int32_t index = 0;
bool found = false;
for (index = 0; index < CIRCUITPY_SUPERVISOR_ALLOC_COUNT; index++) {
found = allocation == &allocations[index];
if (found) {
break;
}
}
if (!found) {
// Bad!
// TODO(tannewt): Add a way to escape into safe mode on error.
}
if (allocation->ptr == high_address) {
high_address += allocation->length / 4;
for (index++; index < CIRCUITPY_SUPERVISOR_ALLOC_COUNT; index++) {
if (allocations[index].ptr != NULL) {
break;
}
high_address += allocations[index].length / 4;
}
} else if (allocation->ptr + allocation->length / 4 == low_address) {
low_address = allocation->ptr;
for (index--; index >= 0; index--) {
if (allocations[index].ptr != NULL) {
break;
}
low_address -= allocations[index].length / 4;
}
} else {
// Freed memory isn't in the middle so skip updating bounds. The memory will be added to the
// middle when the memory to the inside is freed.
}
allocation->ptr = NULL;
}
supervisor_allocation* allocate_remaining_memory(void) {
if (low_address == high_address) {
return NULL;
}
return allocate_memory((high_address - low_address) * 4, false);
}
supervisor_allocation* allocate_memory(uint32_t length, bool high) {
if ((high_address - low_address) * 4 < (int32_t) length || length % 4 != 0) {
return NULL;
}
uint8_t index = 0;
int8_t direction = 1;
if (high) {
index = CIRCUITPY_SUPERVISOR_ALLOC_COUNT - 1;
direction = -1;
}
for (; index < CIRCUITPY_SUPERVISOR_ALLOC_COUNT; index += direction) {
if (allocations[index].ptr == NULL) {
break;
}
}
if (index >= CIRCUITPY_SUPERVISOR_ALLOC_COUNT) {
return NULL;
}
supervisor_allocation* alloc = &allocations[index];
if (high) {
high_address -= length / 4;
alloc->ptr = high_address;
} else {
alloc->ptr = low_address;
low_address += length / 4;
}
alloc->length = length;
return alloc;
}
void supervisor_move_memory(void) {
supervisor_display_move_memory();
}