// writes a dir entry to disk
byte write_dir_entry(dir_entry_t* de, byte* buf)
{
dword de_sec_offset;
dword de_sec_start;
byte b;
word cluster_rev;
dword filesize_rev;
de_sec_offset = de->entry_addr % 512;
de_sec_start = de->entry_addr - de_sec_offset;
b = read_block(buf, de_sec_start);
memreverse((void*)&(de->first_cluster), &cluster_rev, 2);
memreverse((void*)&(de->filesize), &filesize_rev, 4);
// enter dir_entry info into buffer (based on http://en.wikipedia.org/wiki/8.3_filename)
memmove(buf+de_sec_offset, de->filename, 11);
memmove(buf+de_sec_offset+0x0b, &(de->attributes), 1);
memmove(buf+de_sec_offset+0x0c, &(de->unused_attr), 14);
memmove(buf+de_sec_offset+0x1a, &cluster_rev, 2);
memmove(buf+de_sec_offset+0x1c, &filesize_rev, 4);
if(!write_block(buf, de_sec_start))
{
#if DEBUG
pmsg("problem writing direntry!\r\n");
#endif
return 0;
}
return 1;
}
// sets FAT[_cluster_] to 0x00 and returns FAT[_cluster_]'s original value
word clear_FAT(byte* buf, word cluster)
{
dword abs_addr;
dword sec_start;
word ori_cluster;
abs_addr = prtn.FAT_addr + cluster*2;
sec_start = abs_addr - (abs_addr % 512);
if(!read_block(buf, sec_start))
{
#if DEBUG
pmsg("Problem clearing FAT!\r\n");
#endif
return 0;
}
memreverse(buf + (abs_addr % 512), &ori_cluster, 2);
memmove(buf + (abs_addr % 512), (word)0, 2);
if (!write_block(buf, sec_start))
{
#if DEBUG
pmsg("Problem clearing FAT!\r\n");
#endif
return 0;
}
return ori_cluster;
}
// make FAT[_cluster_] point to cluster _value_
byte update_FAT(byte* buf, word cluster, word value)
{
dword abs_addr;
dword sec_start;
word value_rev;
memreverse(&value, &value_rev, 2);
abs_addr = prtn.FAT_addr + cluster*2;
sec_start = abs_addr - (abs_addr % 512);
if(!read_block(buf, sec_start))
{
#if DEBUG
pmsg("Problem updating FAT!\r\n");
#endif
return 0;
}
memmove(buf + (abs_addr % 512), &value_rev, 2);
if (!write_block(buf, sec_start))
{
#if DEBUG
pmsg("Problem updating FAT!\r\n");
#endif
return 0;
}
return 1;
}
void
HdrImage::FlipX()
{
for (int y = 0; y < mHeight; y++) {
memreverse(mData+y*mWidth, mWidth, sizeof(rgba));
}
}
byte getFile(dir_entry_t* de, byte* buf, char* filename, byte length)
{
int i,j;
word cluster;
dword file_size;
byte b;
char filename_upper[12];
for (i = 0; i < prtn.root_dir_size/512; i++)
{
b = read_block(buf, prtn.root_dir_addr + i*512);
for(j = 0; j < 16; j++)
{
if (*(buf + j*32)==0 || *(buf + j*32)==0x2e || *(buf + j*32)==0xe5)
{ continue; }
strncpy(filename_upper, (char*)(buf+j*32), 11);
filename_upper[11] = '\0';
if(strcmp(filename, str_toupper(filename_upper)) == 0)
{
#if DEBUG
pmsg("found file!\r\n");
#endif
memreverse(buf + j*32 + 0x1c, &file_size, 4);
memreverse(buf + j*32 + 0x1a, &cluster, 2);
#if DEBUG
pmsg("cluster numer:"); disword_dec(cluster); pmsg("\r\n");
#endif
// fill in dir_entry
memmove(de->filename, filename, length);
de->attributes = *(buf + j*32 + 0x0b);
memmove(de->unused_attr, buf + j*32 + 0x0c, 14);
de->filesize = file_size;
de->entry_addr = prtn.root_dir_addr + i*512 + j*32;
de->first_cluster = cluster;
return 1;
}
}
}
return 0;
}
word next_clus(word clus, byte *buf)
{
dword addr;
word next;
addr = prtn.FAT_addr + 2*clus;
if(!read_block(buf, addr - addr % 512))
{
#if DEBUG
pmsg("next_clus failed when reading block!\r\n");
#endif
return 0;
}
memreverse(buf + addr%512, &next, 2);
return next;
}
void
HdrImage::FlipXY()
{
memreverse(mData, mWidth*mHeight, sizeof(rgba));
}
int main(int argc, char *argv[]) {
char str[8] = "Hello !";
memreverse(str, 2, 3);
puts(str);
return 0;
}
