HariboteOS/day19/fs.c
2021-04-19 21:41:39 +08:00

29 lines
625 B
C

#include "fs.h"
void file_read_fat(int *fat, unsigned char *img) {
int i, j = 0;
for (i = 0; i < 2880; i += 2) {
fat[i + 0] = (img[j + 0] | img[j + 1] << 8) & 0xfff;
fat[i + 1] = (img[j + 1] >> 4 | img[j + 2] << 4) & 0xfff;
j += 3;
}
}
void file_load_file(int clustno, int size, char *buf, int *fat, char *img) {
for (;;) {
if (size <= 512) {
for (int i = 0; i < size; i++) {
buf[i] = img[clustno * 512 + i];
}
break;
}
for (int i = 0; i < 512; i++) {
buf[i] = img[clustno * 512 + i];
}
size -= 512;
buf += 512;
clustno = fat[clustno];
}
}