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/*
Système Digital
2013-2014
Alex AUVOLAT
sim.c The code that actually runs the machine
*/
#include <stdlib.h>
#include <stdio.h>
#include "sim.h"
#define DEBUG 1
// Util
int pow2(int exp) {
if (exp == 0) return 1;
if (exp == 1) return 2;
int k = pow2(exp / 2);
return (exp % 2 == 0 ? k * k : 2 * k * k);
}
// The code
t_machine *init_machine (t_program *p) {
int i, j;
t_machine *m = malloc(sizeof(t_machine));
m->prog = p;
// Allocate variables
m->var_values = malloc(p->n_vars * sizeof(t_value));
for (i = 0; i < p->n_vars; i++) {
m->var_values[i] = 0;
if (p->vars[i].name[0] == '$') {
// setup constant value
t_value a = 1;
char *o = p->vars[i].name + 1;
while (*o) {
m->var_values[i] |= a;
a >>= 1;
o++;
}
}
}
// Allocate space for registers and rams
m->reg_data = malloc(p->n_regs * sizeof(t_value));
for (i = 0; i < p->n_regs; i++) {
m->reg_data[i] = 0;
}
m->ram_data = malloc(p->n_rams * sizeof(t_value*));
for (i = 0; i < p->n_rams; i++) {
m->ram_data[i] = malloc(pow2(p->rams[i].addr_size) * sizeof(t_value));
for (j = 0; j < pow2(p->rams[i].addr_size); j++) {
m->ram_data[i][j] = 0;
}
}
return m;
}
t_value read_bool(FILE *stream, t_value *mask) {
t_value r = 0;
t_value pow = 1;
char c;
if (mask != NULL) *mask = 0;
for(;;) {
fscanf(stream, "%c", &c);
if (c == '1') {
r |= pow;
} else if (c != '0') {
break;
}
if (mask != NULL) (*mask) |= pow;
pow *= 2;
}
return r;
}
void read_inputs(t_machine *m, FILE *stream) {
/* FORMAT :
For each input in the list, *in the order specified*,
either '/' followed by the decimal value
or the binary value
*/
int i;
t_id var;
t_program *p = m->prog;
if (p->n_inputs == 0) return; // nothing to do
for (i = 0; i < p->n_inputs; i++) {
var = p->inputs[i];
fscanf(stream, " ");
if (fscanf(stream, "/%lu", &(m->var_values[var]))) {
// ok, value is read
} else {
m->var_values[var] = read_bool(stream, NULL);
}
m->var_values[var] &= p->vars[var].mask;
}
}
void machine_step(t_machine *m) {
int i, j;
t_value a, b, c, d, e, ma, mb, v;
t_program *p = m->prog;
// READ REGISTERS && MEMORY
for (i = 0; i < p->n_regs; i++) {
m->var_values[p->regs[i].dest] = m->reg_data[i];
if (DEBUG) fprintf(stderr, "%s <- reg %s : %lx\n",
p->vars[p->regs[i].dest].name,
p->vars[p->regs[i].dest].name,
m->reg_data[i]);
}
for (i = 0; i < p->n_rams; i++) {
e = m->var_values[p->rams[i].write_enable];
if (e == 0) {
a = m->var_values[p->rams[i].read_addr];
b = m->ram_data[i][a];
m->var_values[p->rams[i].dest] = b;
if (DEBUG) fprintf(stderr, "Read ram %lx = %lx\n", a, b);
}
}
// DO THE LOGIC
for (i = 0; i < p->n_eqs; i++) {
v = 0;
switch (p->eqs[i].type) {
case C_COPY:
v = m->var_values[p->eqs[i].Copy.a];
break;
case C_NOT:
v = ~m->var_values[p->eqs[i].Not.a];
break;
case C_BINOP:
a = m->var_values[p->eqs[i].Binop.a];
b = m->var_values[p->eqs[i].Binop.b];
if (p->eqs[i].Binop.op == OP_OR) v = a | b;
if (p->eqs[i].Binop.op == OP_AND) v = a & b;
if (p->eqs[i].Binop.op == OP_XOR) v = a ^ b;
if (p->eqs[i].Binop.op == OP_NAND) v = ~(a & b);
break;
case C_MUX:
a = m->var_values[p->eqs[i].Mux.a];
b = m->var_values[p->eqs[i].Mux.b];
c = m->var_values[p->eqs[i].Mux.c];
ma = m->prog->vars[p->eqs[i].Mux.a].mask;
if (ma == 1) {
v = (a ? c : b);
} else {
v = (a & c) | (~a & b);
}
break;
case C_ROM:
// TODO
break;
case C_CONCAT:
a = m->var_values[p->eqs[i].Concat.a];
b = m->var_values[p->eqs[i].Concat.b];
ma = p->vars[p->eqs[i].Concat.a].mask;
mb = p->vars[p->eqs[i].Concat.b].mask;
b <<= p->eqs[i].Concat.shift;
v = a | b;
if (DEBUG) fprintf (stderr, "concat %lx (&%lx) %lx (&%lx) <%d = %lx .. ",
a, ma, b, mb, p->eqs[i].Concat.shift, v);
break;
case C_SLICE:
a = m->var_values[p->eqs[i].Slice.source];
ma = 1;
mb = 0;
for (j = 0; j <= p->eqs[i].Slice.end; j++) {
if (j >= p->eqs[i].Slice.begin) mb |= ma;
ma <<= 1;
}
v = (a & mb) >> p->eqs[i].Slice.begin;
if (DEBUG) fprintf(stderr, "slice %d-%d m=%lx %lx->%lx .. ",
p->eqs[i].Slice.begin,
p->eqs[i].Slice.end,
mb, a, v);
break;
case C_SELECT:
a = m->var_values[p->eqs[i].Select.source];
v = (a >> p->eqs[i].Select.i) & 1;
if (DEBUG) fprintf(stderr, "select %d %lx->%lx .. ",
p->eqs[i].Select.i, a, v);
break;
}
m->var_values[p->eqs[i].dest_var] = v & (p->vars[p->eqs[i].dest_var].mask);
if (DEBUG) fprintf(stderr, "%s &%lx : %lx\n",
p->vars[p->eqs[i].dest_var].name,
p->vars[p->eqs[i].dest_var].mask,
m->var_values[p->eqs[i].dest_var]);
}
// SAVE REGISTERS && MEMORY
for (i = 0; i < p->n_regs; i++) {
m->reg_data[i] = m->var_values[p->regs[i].source];
if (DEBUG) printf("reg %s <- %s : %lx\n",
p->vars[p->regs[i].dest].name,
p->vars[p->regs[i].source].name,
m->reg_data[i]);
}
for (i = 0; i < p->n_rams; i++) {
e = m->var_values[p->rams[i].write_enable];
if (e != 0) {
a = m->var_values[p->rams[i].write_addr];
d = m->var_values[p->rams[i].data];
m->ram_data[i][a] = d;
if (DEBUG) fprintf(stderr, "Write ram %lx = %lx\n", a, d);
}
}
}
void write_outputs(t_machine *m, FILE *stream) {
/* FORMAT :
For each output value, a line in the form
var_name binary_value decimal_value
*/
int i;
t_id var;
t_program *p = m->prog;
for (i = 0; i < p->n_outputs; i++) {
var = p->outputs[i];
fprintf(stream, "%s\t", p->vars[var].name);
t_value v = m->var_values[var];
t_value mask = p->vars[var].mask;
while (mask > 0) {
fprintf(stream, "%d", v & 1);
v >>= 1;
mask >>= 1;
}
fprintf(stream, "\t%ld\n", m->var_values[var]);
}
fprintf(stream, "\n");
}
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