eeprom_transient.c

 1/* Copyright 2019 Nick Brassel (tzarc)
 2 *
 3 * This program is free software: you can redistribute it and/or modify
 4 * it under the terms of the GNU General Public License as published by
 5 * the Free Software Foundation, either version 2 of the License, or
 6 * (at your option) any later version.
 7 *
 8 * This program is distributed in the hope that it will be useful,
 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
15 */
16
17#include <stdint.h>
18#include <string.h>
19
20#include "eeprom_driver.h"
21#include "eeprom_transient.h"
22
23__attribute__((aligned(4))) static uint8_t transientBuffer[TRANSIENT_EEPROM_SIZE] = {0};
24
25size_t clamp_length(intptr_t offset, size_t len) {
26    if (offset + len > TRANSIENT_EEPROM_SIZE) {
27        len = TRANSIENT_EEPROM_SIZE - offset;
28    }
29
30    return len;
31}
32
33void eeprom_driver_init(void) {}
34
35void eeprom_driver_format(bool erase) {
36    /* The transient eeprom driver doesn't necessarily need to be formatted before use, and it always starts up filled with zeros, due to placement in the .bss section */
37    if (erase) {
38        eeprom_driver_erase();
39    }
40}
41
42void eeprom_driver_erase(void) {
43    memset(transientBuffer, 0x00, TRANSIENT_EEPROM_SIZE);
44}
45
46void eeprom_read_block(void *buf, const void *addr, size_t len) {
47    intptr_t offset = (intptr_t)addr;
48    memset(buf, 0x00, len);
49    len = clamp_length(offset, len);
50    if (len > 0) {
51        memcpy(buf, &transientBuffer[offset], len);
52    }
53}
54
55void eeprom_write_block(const void *buf, void *addr, size_t len) {
56    intptr_t offset = (intptr_t)addr;
57    len             = clamp_length(offset, len);
58    if (len > 0) {
59        memcpy(&transientBuffer[offset], buf, len);
60    }
61}