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/* main.c
* Created: 2023-09-02
* Author: Aryadev Chavali
* Description: Entrypoint of compiler
*/
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MEMORY_DEFAULT 30000
typedef struct
{
size_t dp;
uint8_t memory[MEMORY_DEFAULT];
} machine_t;
bool usable_character(char c)
{
return c == '>' || c == '<' || c == '+' || c == '-' || c == '-' || c == '.' ||
c == ',' || c == '[' || c == ']';
}
typedef struct AST
{
size_t col, row;
enum
{
NEXT = 0,
PREV,
INC,
DEC,
OUT,
READ,
LIN,
LOUT
} type;
int loop_ref;
} node_t;
typedef struct Buffer
{
const char *name;
size_t size;
char data[];
} buffer_t;
buffer_t *buffer_init_str(const char *name, const char *str, size_t str_size)
{
buffer_t *buf = malloc(sizeof(*buf) + str_size + 1);
buf->name = name;
buf->size = str_size;
memcpy(buf->data, str, str_size);
buf->data[str_size] = '\0';
return buf;
}
void print_error(const char *handle, size_t row, size_t column,
const char *reason)
{
fprintf(stderr, "%s:%lu:%lu:%s\n", handle, row, column, reason);
}
struct PResult
{
node_t *nodes;
size_t size;
} parse_input(buffer_t *buffer)
{
node_t *nodes = NULL;
size_t usable = 0, loops = 0;
for (size_t i = 0; i < buffer->size; ++i)
if (usable_character(buffer->data[i]))
{
++usable;
if (buffer->data[i] == '[')
++loops;
}
nodes = calloc(usable, sizeof(*nodes));
// First pass: Get my info
for (size_t i = 0, col = 0, row = 1, nptr = 0; i < buffer->size; ++i)
{
++col;
if (buffer->data[i] == '\n')
{
++row;
col = 0;
}
else if (usable_character(buffer->data[i]))
{
nodes[nptr].col = col;
nodes[nptr].row = row;
switch (buffer->data[i])
{
case '>':
nodes[nptr].type = NEXT;
break;
case '<':
nodes[nptr].type = PREV;
break;
case '+':
nodes[nptr].type = INC;
break;
case '-':
nodes[nptr].type = DEC;
break;
case '.':
nodes[nptr].type = OUT;
break;
case ',':
nodes[nptr].type = READ;
break;
case '[':
nodes[nptr].type = LIN;
nodes[nptr].loop_ref = -1;
break;
case ']':
nodes[nptr].type = LOUT;
nodes[nptr].loop_ref = -1;
break;
}
++nptr;
}
}
// Second pass: setup any loop references
node_t *stack[loops];
memset(stack, 0, loops);
size_t stackptr = 0;
for (size_t i = 0; i < usable; ++i)
{
node_t *node = nodes + i;
if (node->type == LIN)
stack[stackptr++] = node;
else if (node->type == LOUT)
{
if (stackptr == 0)
{
print_error(buffer->name, node->row, node->col,
"ERROR: Unbalanced square brackets!");
goto error;
}
// Access last IN loop
--stackptr;
node->loop_ref = stack[stackptr] - nodes;
stack[stackptr]->loop_ref = i;
}
}
if (stackptr > 0)
{
node_t *node = nodes + usable - 1;
print_error(buffer->name, node->row, node->col,
"ERROR: Unbalanced square brackets!");
goto error;
}
return (struct PResult){nodes, usable};
error:
if (nodes)
free(nodes);
return (struct PResult){0};
}
char *ast_to_str(node_t *ast, size_t size)
{
char *out = calloc(size + 1, 1);
for (size_t i = 0; i < size; ++i)
{
switch (ast[i].type)
{
case NEXT:
out[i] = '>';
break;
case PREV:
out[i] = '<';
break;
case INC:
out[i] = '+';
break;
case DEC:
out[i] = '-';
break;
case OUT:
out[i] = '.';
break;
case READ:
out[i] = ',';
break;
case LIN:
out[i] = '[';
break;
case LOUT:
out[i] = ']';
break;
}
}
out[size] = '\0';
return out;
}
#define MAX(a, b) (a > b ? a : b)
char *fread_all(FILE *fp)
{
const size_t CHUNK_SIZE = 1024, MULT = 2;
struct
{
char *data;
size_t used, available;
} buffer = {calloc(CHUNK_SIZE, sizeof(*buffer.data)), 0, CHUNK_SIZE};
size_t acc = 0, bytes_read = 0;
while ((bytes_read = fread(buffer.data + acc, sizeof(*buffer.data),
CHUNK_SIZE, fp)) != 0)
{
buffer.used += bytes_read;
acc += bytes_read;
if (buffer.used + CHUNK_SIZE >= buffer.available)
{
buffer.available = MAX(buffer.available * MULT, buffer.used + CHUNK_SIZE);
buffer.data = realloc(buffer.data, buffer.available);
}
}
buffer.data = realloc(buffer.data, buffer.used + 1);
buffer.data[buffer.used] = '\0';
return buffer.data;
}
int main(void)
{
const char *filepath = "./input.txt";
FILE *handle = fopen(filepath, "r");
char *file_data = fread_all(handle);
fclose(handle);
buffer_t *buffer = buffer_init_str(filepath, file_data, strlen(file_data));
struct PResult res = parse_input(buffer);
if (res.nodes == NULL)
{
fputs("Exiting early...\n", stderr);
goto error;
}
char *str = ast_to_str(res.nodes, res.size);
free(str);
free(res.nodes);
free(buffer);
free(file_data);
return 0;
error:
if (buffer)
free(buffer);
if (res.nodes)
free(res.nodes);
return 1;
}
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