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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 0
// 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;
m->var_values = malloc(p->n_vars * sizeof(t_value));
for (i = 0; i < p->n_vars; i++) {
m->var_values[i] = 0;
}
m->mem_data = malloc(p->n_eqs * sizeof(t_value));
for (i =0; i < p->n_eqs; i++) {
if (p->eqs[i].type == C_REG) {
m->mem_data[i].RegVal = 0;
} else if (p->eqs[i].type == C_RAM) {
m->mem_data[i].RamData = malloc(pow2(p->eqs[i].Ram.addr_size) * sizeof(t_value));
for (j = 0; j < pow2(p->eqs[i].Ram.addr_size); j++) {
m->mem_data[i].RamData[j] = 0;
}
} else {
// Leave uninitialized. Not as if anybody cares.
}
}
return m;
}
void read_inputs(t_machine *m, FILE *stream) {
/* FORMAT :
For each input in the list, *in the order specified*,
the binary value for that variable.
*/
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, " ");
m->var_values[var] = read_bool(stream, NULL);
}
}
t_value get_var(t_machine *m, t_arg a) {
if (a.mask == 0) return m->var_values[a.SrcVar];
return a.Val;
}
t_value get_mask(t_machine *m, t_arg a) {
if (a.mask == 0) return m->prog->vars[a.SrcVar].mask;
return a.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_eqs; i++) {
if (p->eqs[i].type == C_REG) {
m->var_values[p->eqs[i].dest_var] = m->mem_data[i].RegVal;
} else if (p->eqs[i].type == C_RAM) {
e = get_var(m, p->eqs[i].Ram.write_enable);
if (e == 0) {
a = get_var(m, p->eqs[i].Ram.read_addr);
m->var_values[p->eqs[i].dest_var] = m->mem_data[i].RamData[a];
if (DEBUG) fprintf(stderr, "Read ram %lx = %lx\n", a, m->mem_data[i].RamData[a]);
}
}
}
// DO THE LOGIC
for (i = 0; i < p->n_eqs; i++) {
if (p->eqs[i].type == C_REG || p->eqs[i].type == C_RAM) continue;
v = 0;
switch (p->eqs[i].type) {
case C_ARG:
v = get_var(m, p->eqs[i].Arg.a);
break;
case C_NOT:
v = ~get_var(m, p->eqs[i].Not.a);
break;
case C_BINOP:
a = get_var(m, p->eqs[i].Binop.a);
b = get_var(m, 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 = get_var(m, p->eqs[i].Mux.a);
b = get_var(m, p->eqs[i].Mux.b);
c = get_var(m, p->eqs[i].Mux.c);
ma = get_mask(m, p->eqs[i].Mux.a);
if (ma == 1) {
v = (a ? c : b);
} else {
v = (a & c) | (~a & b);
}
break;
case C_ROM:
// TODO
break;
case C_CONCAT:
a = get_var(m, p->eqs[i].Concat.a);
b = get_var(m, p->eqs[i].Concat.b);
ma = get_mask(m, p->eqs[i].Concat.a);
mb = get_mask(m, p->eqs[i].Concat.b);
while (ma & mb) {
mb <<= 1;
b <<= 1;
}
v = (a & ma) | (b & mb);
if (DEBUG) fprintf (stderr, "concat %lx (%lx), %lx (%lx) = %lx .. ", a, ma, b, mb, v);
break;
case C_SLICE:
a = get_var(m, 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 = get_var(m, 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_eqs; i++) {
if (p->eqs[i].type == C_REG) {
m->mem_data[i].RegVal = m->var_values[p->eqs[i].Reg.var];
} else if (p->eqs[i].type == C_RAM) {
e = get_var(m, p->eqs[i].Ram.write_enable);
if (e != 0) {
a = get_var(m, p->eqs[i].Ram.write_addr);
d = get_var(m, p->eqs[i].Ram.data);
printf("Write ram %lx = %lx\n", a, d);
m->mem_data[i].RamData[a] = d;
}
}
}
}
void write_outputs(t_machine *m, FILE *stream) {
/* FORMAT :
For each output value, a line in the form
var_name binary_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, "\n");
}
fprintf(stream, "\n");
}
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