dos33fsprogs/utils/prodos-utils/prodos_volume_bitmap.c
Vince Weaver 62f80a60fc prodos: fix bug when findind free block
meant that SAVE was not working quite right

also added a bunch of debugging messages
2021-08-05 14:00:46 -04:00

228 lines
4.9 KiB
C

#include <stdio.h>
#include <time.h>
#include "prodos.h"
extern int debug;
/* Note: PRODOS seems to label things this way */
/* block 0123 4567 */
/* 0x0f = 0000 1111 */
static int ones_lookup[16]={
/* 0x0 = 0000 */ 0,
/* 0x1 = 0001 */ 1,
/* 0x2 = 0010 */ 1,
/* 0x3 = 0011 */ 2,
/* 0x4 = 0100 */ 1,
/* 0x5 = 0101 */ 2,
/* 0x6 = 0110 */ 2,
/* 0x7 = 0111 */ 3,
/* 0x8 = 1000 */ 1,
/* 0x9 = 1001 */ 2,
/* 0xA = 1010 */ 2,
/* 0xB = 1011 */ 3,
/* 0xC = 1100 */ 2,
/* 0xD = 1101 */ 3,
/* 0xE = 1110 */ 3,
/* 0xF = 1111 */ 4,
};
/* could be replaced by "find leading 1" instruction */
/* Note we are reverse from usual, wanting MSB first */
/* if available */
static int find_first_one(unsigned char byte) {
int i=0;
if (byte==0) return -1;
while((byte & (0x80>>i))==0) {
i++;
}
return i;
}
/* Return how many bytes free in the filesystem */
/* by reading the VTOC_FREE_BITMAP */
int prodos_voldir_free_space(struct voldir_t *voldir) {
int volblocks;
unsigned char temp_block[PRODOS_BYTES_PER_BLOCK];
int i,j,blocks_free=0;
volblocks=1+voldir->total_blocks/(PRODOS_BYTES_PER_BLOCK*8);
for(j=0;j<volblocks;j++) {
prodos_read_block(voldir,temp_block,j+voldir->bit_map_pointer);
for(i=0;i<PRODOS_BYTES_PER_BLOCK;i++) {
blocks_free+=ones_lookup[temp_block[i]&0xf];
blocks_free+=ones_lookup[(temp_block[i]>>4)&0xf];
}
}
return blocks_free;
}
/* free a block from the block bitmap */
int prodos_voldir_free_block(struct voldir_t *voldir, int block) {
/* each volblock holds 512*8=4k entries */
/* block location = block%4096 */
/* which byte=remainder/8 */
int volblock;
unsigned char temp_block[PRODOS_BYTES_PER_BLOCK];
unsigned char bitmap;
int which_bitmap;
volblock=block/(PRODOS_BYTES_PER_BLOCK*8);
prodos_read_block(voldir,temp_block,volblock+voldir->bit_map_pointer);
which_bitmap=(block%(PRODOS_BYTES_PER_BLOCK*8))/8;
bitmap=temp_block[which_bitmap];
if (debug) {
printf("Free: $%X Using volblock %d (%d), flip b[%d]#%d $%X ",
block,volblock,volblock+voldir->bit_map_pointer,
which_bitmap,block&7,bitmap);
}
/* set bit to 1 to mark free */
bitmap|=(0x80>>(block&7));
if (debug) {
printf("-> $%X\n",bitmap);
}
temp_block[which_bitmap]=bitmap;
prodos_write_block(voldir,temp_block,volblock+voldir->bit_map_pointer);
return 0;
}
/* reserve a block in the block bitmap */
int prodos_voldir_reserve_block(struct voldir_t *voldir, int block) {
/* each volblock holds 512*8=4k entries */
/* block location = block%4096 */
/* which byte=remainder/8 */
int volblock;
unsigned char temp_block[PRODOS_BYTES_PER_BLOCK];
unsigned char bitmap;
int which_bitmap;
volblock=block/(PRODOS_BYTES_PER_BLOCK*8);
prodos_read_block(voldir,temp_block,volblock+voldir->bit_map_pointer);
which_bitmap=(block%(PRODOS_BYTES_PER_BLOCK*8))/8;
bitmap=temp_block[which_bitmap];
if (debug) {
printf("Reserve: $%X Using volblock %d (%d), flip b[%d]#%d $%X ",
block,volblock,volblock+voldir->bit_map_pointer,
which_bitmap,block&7,bitmap);
}
/* clear bit to 0 to mark used */
bitmap&=~(0x80>>(block&7));
if (debug) {
printf("-> $%X\n",bitmap);
}
temp_block[which_bitmap]=bitmap;
prodos_write_block(voldir,temp_block,volblock+voldir->bit_map_pointer);
return 0;
}
void prodos_voldir_dump_bitmap(struct voldir_t *voldir) {
int volblocks;
unsigned char temp_block[PRODOS_BYTES_PER_BLOCK];
int i,j,k;
volblocks=1+voldir->total_blocks/(PRODOS_BYTES_PER_BLOCK*8);
for(k=0;k<volblocks;k++) {
printf("\nFree block bitmap Block %d (block %d/%d):\n",
k+voldir->bit_map_pointer,k+1,volblocks);
printf("\tU=used, .=free\n");
printf("\tBlock 01234567 89ABCDEF\n");
prodos_read_block(voldir,temp_block,k+voldir->bit_map_pointer);
for(i=0;i<(512/16);i++) {
printf("\t $%03X: %02X %02X : ",i,
temp_block[(i*2)],
temp_block[(1+i*2)]);
for(j=0;j<8;j++) {
if ((temp_block[i*2]>>(7-j))&0x1) {
printf(".");
}
else {
printf("U");
}
}
printf(" ");
for(j=0;j<8;j++) {
if ((temp_block[(1+i*2)]>>(7-j))&0x1) {
printf(".");
}
else {
printf("U");
}
}
printf("\n");
}
}
}
/* find a free block in the block bitmap */
/* FIXME: for speed, remember last found block and start from there */
int prodos_voldir_find_free_block(struct voldir_t *voldir) {
int volblocks;
unsigned char temp_block[PRODOS_BYTES_PER_BLOCK];
int i,k,result;
volblocks=1+voldir->total_blocks/(PRODOS_BYTES_PER_BLOCK*8);
for(k=0;k<volblocks;k++) {
prodos_read_block(voldir,temp_block,k+voldir->bit_map_pointer);
for(i=0;i<(512/16);i++) {
result=find_first_one(temp_block[i*2]);
if (result>=0) {
if (debug) printf("Found free block %x\n",
(k<<12)+(i<<4)+result);
return (k<<12)+(i<<4)+result;
}
result=find_first_one(temp_block[(1+i*2)]);
if (result>=0) {
if (debug) printf("Found free block %x\n",
(k<<12)+(i<<4)+result+8);
return (k<<12)+(i<<4)+result+8;
}
}
}
/* no room */
return -1;
}