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/* yForth? - Written by Luca Padovani (C) 1996/97
* ------------------------------------------------------------------------
* This software is FreeWare as long as it comes with this header in each
* source file, anyway you can use it or any part of it whatever
* you want. It comes without any warranty, so use it at your own risk.
* ------------------------------------------------------------------------
* Module name: block.c
* Abstract: Block word set implementation
*/
#include <stdio.h>
#include <malloc.h>
#include "yforth.h"
#include "core.h"
#include "block.h"
/**************************************************************************/
/* VARIABLES **************************************************************/
/**************************************************************************/
UCell _b_l_k;
UCell current_block;
FILE *block_file; /* FILE used to implement blocks */
struct _block_data *block_data;
struct _block_buffer *block_buffer;
static int block_clock; /* Used to select the next block to
deallocate. Based on the "clock
algorithm
*/
/**************************************************************************/
/* WORDS ******************************************************************/
/**************************************************************************/
void _block() {
register UCell u = (UCell) *sp;
register int b = search_block(u);
if (b < 0) b = allocate_block(u, 1);
current_block = b;
sp[0] = (Cell) &block_buffer[b].buffer;
}
void _buffer() {
register UCell u = (UCell) *sp;
register int b = search_block(u);
if (b < 0) b = allocate_block(u, 0);
current_block = b;
sp[0] = (Cell) &block_buffer[b].buffer;
}
void _flush() {
register int i;
_save_buffers();
for (i = 0; i < NUM_BLOCKS; i++) block_data[i].block_no = 0;
}
void _load() {
register UCell block_no = (UCell) *sp;
save_input_specification();
_block();
_input_buffer = (Char *) *sp++;
_in_input_buffer = BLOCK_SIZE;
_to_in = 0;
_b_l_k = block_no;
_interpret();
restore_input_specification();
}
void _save_buffers() {
register int i;
for (i = 0; i < NUM_BLOCKS; i++) if (block_data[i].dirty) save_block(i);
}
void _update() {
block_data[current_block].dirty = 1;
}
/**************************************************************************/
/* AUXILIARY FUNCTIONS ****************************************************/
/**************************************************************************/
int search_block(UCell block_no) {
register int i;
for (i = 0; i < NUM_BLOCKS && block_data[i].block_no != block_no; i++) ;
return (i < NUM_BLOCKS ? i : -1);
}
int allocate_block(UCell block_no, int load) {
register int i;
register int b = search_block(0);
if (b < 0) {
if (block_data[block_clock].dirty) save_block(block_clock);
b = block_clock;
block_clock = (block_clock + 1) % NUM_BLOCKS;
}
if (load) load_block(block_no, b);
return (b);
}
void load_block(UCell block_no, int b) {
block_data[b].block_no = block_no;
block_data[b].dirty = 0;
fseek(block_file, ((long) (block_no - 1)) * BLOCK_SIZE, SEEK_SET);
fread(&block_buffer[b].buffer, BLOCK_SIZE, 1, block_file);
}
void save_block(int b) {
fseek(block_file, ((long) (block_data[b].block_no - 1)) * BLOCK_SIZE, SEEK_SET);
fwrite(&block_buffer[b].buffer, BLOCK_SIZE, 1, block_file);
block_data[b].dirty = 0;
}
int open_block_file(char *name) {
block_file = fopen(name, "r+b");
if (!block_file) block_file = fopen(name, "r+b");
if (block_file) {
block_data = (struct _block_data *) malloc(NUM_BLOCKS * sizeof(struct _block_data));
block_buffer = (struct _block_buffer *) malloc(NUM_BLOCKS * sizeof(struct _block_buffer));
if (block_data && block_buffer) {
int i;
for (i = 0; i < NUM_BLOCKS; i++) block_data[i].block_no = 0;
} else block_file = NULL;
}
return (block_file ? 0 : -1);
}
void close_block_file() {
if (block_file) {
_save_buffers();
fclose(block_file);
}
}
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