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chibi-scheme/eval.c
Alex Shinn d609e52e5f using boehm gc by default
2009-03-03 21:41:20 +09:00

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/* eval.c -- evaluator library implementation */
/* Copyright (c) 2009 Alex Shinn. All rights reserved. */
/* BSD-style license: http://synthcode.com/license.txt */
#include "eval.h"
/* ******************************************************************** */
static struct core_form core_forms[] = {
{SEXP_CORE, "define", CORE_DEFINE},
{SEXP_CORE, "set!", CORE_SET},
{SEXP_CORE, "lambda", CORE_LAMBDA},
{SEXP_CORE, "if", CORE_IF},
{SEXP_CORE, "begin", CORE_BEGIN},
{SEXP_CORE, "quote", CORE_QUOTE},
{SEXP_CORE, "define-syntax", CORE_DEFINE_SYNTAX},
{SEXP_CORE, "let-syntax", CORE_LET_SYNTAX},
{SEXP_CORE, "letrec-syntax", CORE_LETREC_SYNTAX},
};
static struct opcode opcodes[] = {
{SEXP_OPCODE, OPC_TYPE_PREDICATE, OP_CAR, 1, 0, SEXP_PAIR, 0, "car", 0, NULL},
{SEXP_OPCODE, OPC_TYPE_PREDICATE, OP_CDR, 1, 0, SEXP_PAIR, 0, "cdr", 0, NULL},
{SEXP_OPCODE, OPC_ARITHMETIC, OP_ADD, 0, 1, SEXP_FIXNUM, 0, "+", 0, NULL},
{SEXP_OPCODE, OPC_ARITHMETIC_INV, OP_SUB, 0, 1, SEXP_FIXNUM, 0, "-", OP_NEG, NULL},
{SEXP_OPCODE, OPC_ARITHMETIC, OP_MUL, 0, 1, SEXP_FIXNUM, 0, "*", 0, NULL},
{SEXP_OPCODE, OPC_ARITHMETIC_INV, OP_DIV, 0, 1, SEXP_FIXNUM, 0, "/", OP_INV, 0},
{SEXP_OPCODE, OPC_ARITHMETIC, OP_MOD, 2, 0, SEXP_FIXNUM, SEXP_FIXNUM, "%", 0, NULL},
{SEXP_OPCODE, OPC_ARITHMETIC_CMP, OP_LT, 0, 1, SEXP_FIXNUM, 0, "<", 0, NULL},
{SEXP_OPCODE, OPC_CONSTRUCTOR, OP_CONS, 2, 0, 0, 0, "cons", 0, NULL},
{SEXP_OPCODE, OPC_CONSTRUCTOR, OP_MAKE_VECTOR, 2, 0, SEXP_FIXNUM, 0, "make-vector", 0, NULL},
{SEXP_OPCODE, OPC_CONSTRUCTOR, OP_MAKE_PROCEDURE, 2, 0, 0, 0, "make-procedure", 0, NULL},
};
#ifdef USE_DEBUG
#include "debug.c"
#else
#define print_stack(...)
#define print_bytecode(...)
#define disasm(...)
#endif
/********************** environment utilities ***************************/
sexp env_cell(env e, sexp key) {
sexp ls, res=NULL;
do {
for (ls=e->bindings; SEXP_PAIRP(ls); ls=SEXP_CDR(ls)) {
if (SEXP_CAAR(ls) == key) {
res = SEXP_CAR(ls);
break;
}
}
e = e->parent;
} while (e && ! res);
return res;
}
int env_global_p (env e, sexp id) {
while (e->parent) {
if (assq(id, e->bindings) != SEXP_FALSE)
return 0;
else
e = e->parent;
}
return 1;
}
void env_define(env e, sexp key, sexp value) {
sexp cell = env_cell(e, key);
if (cell) {
SEXP_CDR(cell) = value;
} else {
e->bindings = cons(cons(key, value), e->bindings);
}
}
env extend_env_closure (env e, sexp fv) {
int i;
env e2 = (env) SEXP_ALLOC(sizeof(struct env));
e2->tag = SEXP_ENV;
e2->parent = e;
e2->bindings = SEXP_NULL;
for (i=0; SEXP_PAIRP(fv); fv = SEXP_CDR(fv), i++) {
e2->bindings = cons(cons(SEXP_CAR(fv), make_integer(i)), e2->bindings);
}
return e2;
}
env make_standard_env() {
int i;
env e = (env) SEXP_ALLOC(sizeof(struct env));
e->tag = SEXP_ENV;
e->parent = NULL;
e->bindings = SEXP_NULL;
for (i=0; i<(sizeof(core_forms)/sizeof(struct core_form)); i++) {
env_define(e, intern(core_forms[i].name), (sexp)(&core_forms[i]));
}
for (i=0; i<(sizeof(opcodes)/sizeof(struct opcode)); i++) {
env_define(e, intern(opcodes[i].name), (sexp)(&opcodes[i]));
}
return e;
}
/************************* bytecode utilities ***************************/
void shrink_bcode(bytecode *bc, unsigned int i) {
bytecode tmp;
if ((*bc)->len != i) {
fprintf(stderr, "shrinking to %d\n", i);
tmp = (bytecode) SEXP_ALLOC(sizeof(struct bytecode) + i);
tmp->tag = SEXP_BYTECODE;
tmp->len = i;
memcpy(tmp->data, (*bc)->data, i);
SEXP_FREE(*bc);
*bc = tmp;
}
}
void emit(bytecode *bc, unsigned int *i, char c) {
bytecode tmp;
if ((*bc)->len < (*i)+1) {
fprintf(stderr, "expanding (%d < %d)\n", (*bc)->len, (*i)+1);
tmp = (bytecode) SEXP_ALLOC(sizeof(unsigned int) + (*bc)->len*2);
tmp->len = (*bc)->len*2;
memcpy(tmp->data, (*bc)->data, (*bc)->len);
SEXP_FREE(*bc);
*bc = tmp;
}
(*bc)->data[(*i)++] = c;
}
void emit_word(bytecode *bc, unsigned int *i, unsigned long val) {
bytecode tmp;
if ((*bc)->len < (*i)+4) {
tmp = (bytecode) SEXP_ALLOC(sizeof(unsigned int) + (*bc)->len*2);
tmp->len = (*bc)->len*2;
memcpy(tmp->data, (*bc)->data, (*bc)->len);
SEXP_FREE(*bc);
*bc = tmp;
}
*((unsigned long*)(&((*bc)->data[*i]))) = val;
*i += sizeof(unsigned long);
}
sexp make_procedure(sexp bc, sexp vars) {
sexp proc = SEXP_NEW();
if (! proc) return SEXP_ERROR;
proc->tag = SEXP_PROCEDURE;
proc->data1 = (void*) bc;
proc->data2 = (void*) vars;
return proc;
}
/************************* the compiler ***************************/
void analyze(sexp obj, bytecode *bc, unsigned int *i, env e,
sexp params, sexp fv, sexp sv, unsigned int *d) {
int tmp1, tmp2;
env e2 = e;
sexp o1, o2, cell;
if (SEXP_PAIRP(obj)) {
/* fprintf(stderr, ":: pair\n"); */
if (SEXP_SYMBOLP(SEXP_CAR(obj))) {
fprintf(stderr, ":: symbol application\n");
o1 = env_cell(e, SEXP_CAR(obj));
/* fprintf(stderr, ":: => %p\n", o1); */
if (! o1)
errx(1, "unknown operator: %s", SEXP_CAR(obj));
o1 = SEXP_CDR(o1);
/* fprintf(stderr, ":: => %p\n", o1); */
if (SEXP_COREP(o1)) {
/* core form */
fprintf(stderr, ":: core form\n");
switch (((core_form)o1)->code) {
case CORE_LAMBDA:
fprintf(stderr, ":: lambda\n");
analyze_lambda(SEXP_FALSE, SEXP_CADR(obj), SEXP_CDDR(obj),
bc, i, e, params, fv, sv, d);
break;
case CORE_DEFINE:
fprintf(stderr, "compiling global set: %p\n", SEXP_CADR(obj));
if ((((core_form)o1)->code == CORE_DEFINE)
&& SEXP_PAIRP(SEXP_CADR(obj))) {
analyze_lambda(SEXP_CAR(SEXP_CADR(obj)),
SEXP_CDR(SEXP_CADR(obj)),
SEXP_CDDR(obj),
bc, i, e, params, fv, sv, d);
} else {
analyze(SEXP_CADDR(obj), bc, i, e, params, fv, sv, d);
}
emit(bc, i, OP_GLOBAL_SET);
emit_word(bc, i, (unsigned long) (SEXP_PAIRP(SEXP_CADR(obj))
? SEXP_CAR(SEXP_CADR(obj))
: SEXP_CADR(obj)));
emit(bc, i, OP_PUSH);
(*d)++;
emit_word(bc, i, (unsigned long) SEXP_UNDEF);
break;
case CORE_SET:
fprintf(stderr, "set!: "); write_sexp(stderr, SEXP_CADR(obj));
fprintf(stderr, " sv: "); write_sexp(stderr, sv);
fprintf(stderr, "\n");
analyze(SEXP_CADDR(obj), bc, i, e, params, fv, sv, d);
analyze_var_ref(SEXP_CADR(obj), bc, i, e, params, fv, SEXP_NULL, d);
emit(bc, i, OP_SET_CAR);
break;
case CORE_BEGIN:
for (o2 = SEXP_CDR(obj); SEXP_PAIRP(o2); o2 = SEXP_CDR(o2)) {
analyze(SEXP_CAR(o2), bc, i, e, params, fv, sv, d);
if (SEXP_PAIRP(SEXP_CDR(o2))) emit(bc, i, OP_DROP);
}
break;
case CORE_IF:
fprintf(stderr, "test clause: %d\n", *i);
analyze(SEXP_CADR(obj), bc, i, e, params, fv, sv, d);
emit(bc, i, OP_JUMP_UNLESS); /* jumps if test fails */
tmp1 = *i;
emit(bc, i, 0);
fprintf(stderr, "pass clause: %d\n", *i);
analyze(SEXP_CADDR(obj), bc, i, e, params, fv, sv, d);
emit(bc, i, OP_JUMP);
tmp2 = *i;
emit(bc, i, 0);
((signed char*) (*bc)->data)[tmp1] = (*i)-tmp1-1; /* patch */
fprintf(stderr, "fail clause: %d\n", *i);
if (SEXP_PAIRP(SEXP_CDDDR(obj))) {
analyze(SEXP_CADDDR(obj), bc, i, e, params, fv, sv, d);
} else {
emit(bc, i, OP_PUSH);
(*d)++;
emit_word(bc, i, (unsigned long) SEXP_UNDEF);
}
((signed char*) (*bc)->data)[tmp2] = (*i)-tmp2-1; /* patch */
break;
case CORE_QUOTE:
emit(bc, i, OP_PUSH);
(*d)++;
emit_word(bc, i, (unsigned long)SEXP_CADR(obj));
break;
default:
errx(1, "unknown core form: %s", ((core_form)o1)->code);
}
} else if (SEXP_OPCODEP(o1)) {
fprintf(stderr, ":: opcode\n");
/* direct opcode */
/* verify arity */
switch (((opcode)o1)->op_class) {
case OPC_TYPE_PREDICATE:
case OPC_PREDICATE:
case OPC_ARITHMETIC:
case OPC_ARITHMETIC_INV:
case OPC_ARITHMETIC_CMP:
if (SEXP_NULLP(SEXP_CDR(obj))) {
errx(1, "unknown opcode class: %d", ((opcode)o1)->op_class);
} else if (SEXP_NULLP(SEXP_CDDR(obj))) {
if (((opcode)o1)->op_class == OPC_ARITHMETIC_INV) {
analyze(SEXP_CADR(obj), bc, i, e, params, fv, sv, d);
emit(bc, i, ((opcode)o1)->op_inverse);
} else {
analyze(SEXP_CADR(obj), bc, i, e, params, fv, sv, d);
}
} else {
/* fprintf(stderr, ":: class: %d\n", ((opcode)o1)->op_class); */
for (o2 = reverse(SEXP_CDR(obj)); SEXP_PAIRP(o2); o2 = SEXP_CDR(o2)) {
/* fprintf(stderr, ":: arg: %d\n", SEXP_CAR(o2)); */
analyze(SEXP_CAR(o2), bc, i, e, params, fv, sv, d);
}
fprintf(stderr, ":: name: %d\n", ((opcode)o1)->op_name);
emit(bc, i, ((opcode)o1)->op_name);
(*d) -= length(SEXP_CDDR(obj));
}
break;
default:
errx(1, "unknown opcode class: %d", ((opcode)o1)->op_class);
}
} else {
/* function call */
analyze_app(obj, bc, i, e, params, fv, sv, d);
}
} else if (SEXP_PAIRP(SEXP_CAR(obj))) {
o2 = env_cell(e, SEXP_CAAR(obj));
/* if (o2 */
/* && SEXP_COREP(SEXP_CDR(o2)) */
/* && (((core_form)SEXP_CDR(o2))->code == CORE_LAMBDA)) { */
/* /\* let *\/ */
/* } else { */
/* computed application */
analyze_app(obj, bc, i, e, params, fv, sv, d);
/* } */
} else {
errx(1, "invalid operator: %s", SEXP_CAR(obj));
}
} else if (SEXP_SYMBOLP(obj)) {
analyze_var_ref(obj, bc, i, e, params, fv, sv, d);
} else {
fprintf(stderr, "push: %d\n", (unsigned long)obj);
emit(bc, i, OP_PUSH);
emit_word(bc, i, (unsigned long)obj);
(*d)++;
}
}
void analyze_var_ref (sexp obj, bytecode *bc, unsigned int *i, env e,
sexp params, sexp fv, sexp sv, unsigned int *d) {
int tmp;
fprintf(stderr, "symbol lookup, param length: %d sv: ", length(params));
write_sexp(stderr, sv);
fprintf(stderr, "\n");
if ((tmp = list_index(params, obj)) >= 0) {
fprintf(stderr, "compiling local ref: %p => %d (d = %d)\n", obj, tmp, *d);
emit(bc, i, OP_STACK_REF);
emit_word(bc, i, tmp + *d + 4);
(*d)++;
} else if ((tmp = list_index(fv, obj)) >= 0) {
fprintf(stderr, "compiling closure ref: %p => %d\n", obj, tmp);
emit(bc, i, OP_CLOSURE_REF);
emit_word(bc, i, tmp);
(*d)++;
} else {
fprintf(stderr, "compiling global ref: %p\n", obj);
emit(bc, i, OP_GLOBAL_REF);
emit_word(bc, i, (unsigned long) obj);
(*d)++;
}
if (list_index(sv, obj) >= 0) {
fprintf(stderr, "mutable variables, fetching CAR\n");
emit(bc, i, OP_CAR);
}
}
void analyze_app (sexp obj, bytecode *bc, unsigned int *i,
env e, sexp params, sexp fv, sexp sv, unsigned int *d) {
sexp o1;
unsigned long len = length(SEXP_CDR(obj));
/* push the arguments onto the stack */
for (o1 = reverse(SEXP_CDR(obj)); SEXP_PAIRP(o1); o1 = SEXP_CDR(o1)) {
analyze(SEXP_CAR(o1), bc, i, e, params, fv, sv, d);
}
/* push the operator onto the stack */
analyze(SEXP_CAR(obj), bc, i, e, params, fv, sv, d);
/* make the call */
emit(bc, i, OP_CALL);
emit_word(bc, i, (unsigned long) make_integer(len));
}
sexp free_vars (env e, sexp formals, sexp obj, sexp fv) {
sexp o1;
if (SEXP_SYMBOLP(obj)) {
if (env_global_p(e, obj)
|| (list_index(formals, obj) >= 0)
|| (list_index(fv, obj) >= 0))
return fv;
else
return cons(obj, fv);
} else if (SEXP_PAIRP(obj)) {
if (SEXP_SYMBOLP(SEXP_CAR(obj))) {
if ((o1 = env_cell(e, SEXP_CAR(obj)))
&& SEXP_COREP(o1)
&& (((core_form)SEXP_CDR(o1))->code == CORE_LAMBDA)) {
return free_vars(e, SEXP_CADR(obj), SEXP_CADDR(obj), fv);
}
}
while (SEXP_PAIRP(obj)) {
fv = free_vars(e, formals, SEXP_CAR(obj), fv);
obj = SEXP_CDR(obj);
}
return fv;
} else {
return fv;
}
}
sexp set_vars (env e, sexp formals, sexp obj, sexp sv) {
sexp tmp;
if (SEXP_NULLP(formals))
return sv;
if (SEXP_PAIRP(obj)) {
if (SEXP_SYMBOLP(SEXP_CAR(obj))) {
if ((tmp = env_cell(e, SEXP_CAR(obj))) && SEXP_COREP(SEXP_CDR(tmp))) {
if (((core_form)SEXP_CDR(tmp))->code == CORE_LAMBDA) {
formals = lset_diff(formals, SEXP_CADR(obj));
return set_vars(e, formals, SEXP_CADDR(obj), sv);
} else if (((core_form)SEXP_CDR(tmp))->code == CORE_SET) {
if ((list_index(formals, SEXP_CADR(obj)) >= 0)
&& ! (list_index(sv, SEXP_CADR(obj)) >= 0)) {
fprintf(stderr, "found set! "); write_sexp(stderr, SEXP_CADR(obj));
fprintf(stderr, "\n");
sv = cons(SEXP_CADR(obj), sv);
return set_vars(e, formals, SEXP_CADDR(obj), sv);
}
}
}
}
while (SEXP_PAIRP(obj)) {
sv = set_vars(e, formals, SEXP_CAR(obj), sv);
obj = SEXP_CDR(obj);
}
}
return sv;
}
void analyze_lambda (sexp name, sexp formals, sexp body,
bytecode *bc, unsigned int *i, env e,
sexp params, sexp fv, sexp sv, unsigned int *d) {
sexp obj;
sexp fv2 = free_vars(e, formals, body, SEXP_NULL), ls;
env e2 = extend_env_closure(e, formals);
int k;
fprintf(stderr, "%d free-vars\n", length(fv2));
write_sexp(stderr, fv2);
fprintf(stderr, "\n");
obj = (sexp) compile(formals, body, e2, fv2, sv, 0);
emit(bc, i, OP_PUSH);
emit_word(bc, i, (unsigned long) SEXP_UNDEF);
emit(bc, i, OP_PUSH);
emit_word(bc, i, (unsigned long) make_integer(length(fv2)));
emit(bc, i, OP_MAKE_VECTOR);
(*d)++;
for (ls=fv2, k=0; SEXP_PAIRP(ls); ls=SEXP_CDR(ls), k++) {
analyze_var_ref(SEXP_CAR(ls), bc, i, e, params, fv, SEXP_NULL, d);
emit(bc, i, OP_PUSH);
emit_word(bc, i, (unsigned long) make_integer(k));
emit(bc, i, OP_STACK_REF);
emit_word(bc, i, 3);
emit(bc, i, OP_VECTOR_SET);
emit(bc, i, OP_DROP);
(*d)--;
}
emit(bc, i, OP_PUSH);
emit_word(bc, i, (unsigned long) obj);
emit(bc, i, OP_MAKE_PROCEDURE);
}
bytecode compile(sexp params, sexp obj, env e, sexp fv, sexp sv, int done_p) {
unsigned int i = 0, j, d = 0;
bytecode bc = (bytecode) SEXP_ALLOC(sizeof(struct bytecode)+INIT_BCODE_SIZE);
sexp sv2 = set_vars(e, params, obj, SEXP_NULL), ls;
fprintf(stderr, "set-vars: "); write_sexp(stderr, sv2); fprintf(stderr, "\n");
bc->tag = SEXP_BYTECODE;
bc->len = INIT_BCODE_SIZE;
fprintf(stderr, "analyzing\n");
for (ls=params; SEXP_PAIRP(ls); ls=SEXP_CDR(ls)) {
if ((j = list_index(sv2, SEXP_CAR(ls)) >= 0)) {
fprintf(stderr, "consing mutable var\n");
emit(&bc, &i, OP_PUSH);
emit_word(&bc, &i, (unsigned long) SEXP_NULL);
emit(&bc, &i, OP_STACK_REF);
emit_word(&bc, &i, j+3);
emit(&bc, &i, OP_CONS);
emit(&bc, &i, OP_STACK_SET);
emit_word(&bc, &i, j+4);
emit(&bc, &i, OP_DROP);
}
}
sv = append(sv2, sv);
for ( ; SEXP_PAIRP(obj); obj=SEXP_CDR(obj)) {
fprintf(stderr, "loop: "); write_sexp(stderr, obj); fprintf(stderr, "\n");
analyze(SEXP_CAR(obj), &bc, &i, e, params, fv, sv, &d);
if (SEXP_PAIRP(SEXP_CDR(obj))) emit(&bc, &i, OP_DROP);
}
emit(&bc, &i, done_p ? OP_DONE : OP_RET);
/* fprintf(stderr, "shrinking\n"); */
shrink_bcode(&bc, i);
fprintf(stderr, "done compiling:\n");
print_bytecode(bc);
disasm(bc);
return bc;
}
/*********************** the virtual machine **************************/
sexp vm(bytecode bc, env e, sexp* stack, unsigned int top) {
unsigned char *ip=bc->data;
sexp cp, tmp;
int i;
loop:
/* fprintf(stderr, "opcode: %d, ip: %d\n", *ip, ip); */
/* print_bytecode(bc); */
switch (*ip++) {
case OP_NOOP:
fprintf(stderr, "noop\n");
break;
case OP_GLOBAL_REF:
fprintf(stderr, "global ref: ip: %p => %p: ", ip, ((sexp*)ip)[0]);
fflush(stderr);
write_sexp(stderr, ((sexp*)ip)[0]);
fprintf(stderr, "\n");
tmp = env_cell(e, ((sexp*)ip)[0]);
stack[top++]=SEXP_CDR(tmp);
ip += sizeof(sexp);
break;
case OP_GLOBAL_SET:
fprintf(stderr, "global set: %p: ", ((sexp*)ip)[0]);
fflush(stderr);
write_sexp(stderr, ((sexp*)ip)[0]);
fprintf(stderr, "\n");
env_define(e, ((sexp*)ip)[0], stack[--top]);
ip += sizeof(sexp);
break;
case OP_STACK_REF:
fprintf(stderr, "stack ref: ip=%p, %d - %d => ",
ip, top, (unsigned long) ((sexp*)ip)[0]);
fflush(stderr);
write_sexp(stderr, stack[top - (unsigned int) ((sexp*)ip)[0]]);
fprintf(stderr, "\n");
stack[top] = stack[top - (unsigned int) ((sexp*)ip)[0]];
ip += sizeof(sexp);
top++;
break;
case OP_STACK_SET:
stack[top - (unsigned int) ((sexp*)ip)[0]] = stack[top-1];
stack[top-1] = SEXP_UNDEF;
ip += sizeof(sexp);
break;
case OP_CLOSURE_REF:
fprintf(stderr, "closure-ref %d => ", ((sexp*)ip)[0]);
fflush(stderr);
write_sexp(stderr, vector_ref(cp,((sexp*)ip)[0]));
fprintf(stderr, "\n");
stack[top++]=vector_ref(cp,((sexp*)ip)[0]);
ip += sizeof(sexp);
break;
case OP_VECTOR_REF:
stack[top-2]=vector_ref(stack[top-1], stack[top-2]);
top--;
break;
case OP_VECTOR_SET:
fprintf(stderr, "vector-set! %p %d => ", stack[top-1], unbox_integer(stack[top-2]));
write_sexp(stderr, stack[top-3]);
fprintf(stderr, "\n");
vector_set(stack[top-1], stack[top-2], stack[top-3]);
stack[top-3]=SEXP_UNDEF;
top-=2;
break;
case OP_MAKE_PROCEDURE:
stack[top-2]=make_procedure(stack[top-1], stack[top-2]);
top--;
break;
case OP_MAKE_VECTOR:
stack[top-2]=make_vector(unbox_integer(stack[top-1]), stack[top-2]);
top--;
break;
case OP_PUSH:
/* fprintf(stderr, " (push)\n"); */
stack[top++]=((sexp*)ip)[0];
ip += sizeof(sexp);
break;
case OP_DUP:
stack[top]=stack[top-1];
top++;
break;
case OP_DROP:
top--;
break;
case OP_SWAP:
tmp = stack[top-2];
stack[top-2]=stack[top-1];
stack[top-1]=tmp;
break;
case OP_CAR:
stack[top-1]=car(stack[top-1]);
break;
case OP_CDR:
stack[top-1]=cdr(stack[top-1]);
break;
case OP_SET_CAR:
set_car(stack[top-1], stack[top-2]);
stack[top-2]=SEXP_UNDEF;
top--;
break;
case OP_SET_CDR:
set_cdr(stack[top-1], stack[top-2]);
stack[top-2]=SEXP_UNDEF;
top--;
break;
case OP_CONS:
stack[top-2]=cons(stack[top-1], stack[top-2]);
top--;
break;
case OP_ADD:
fprintf(stderr, "OP_ADD %d %d\n", stack[top-1], stack[top-2]);
stack[top-2]=sexp_add(stack[top-1],stack[top-2]);
top--;
break;
case OP_SUB:
stack[top-2]=sexp_sub(stack[top-1],stack[top-2]);
top--;
break;
case OP_MUL:
stack[top-2]=sexp_mul(stack[top-2],stack[top-1]);
top--;
break;
case OP_DIV:
stack[top-2]=sexp_div(stack[top-2],stack[top-1]);
top--;
break;
case OP_MOD:
stack[top-2]=sexp_mod(stack[top-2],stack[top-1]);
top--;
break;
case OP_LT:
stack[top-2]=((stack[top-2] < stack[top-1]) ? SEXP_TRUE : SEXP_FALSE);
top--;
break;
case OP_CALL:
fprintf(stderr, "CALL\n");
i = (unsigned long) ((sexp*)ip)[0];
tmp = stack[top-1];
if (! SEXP_PROCEDUREP(tmp))
errx(2, "non-procedure application: %p", tmp);
stack[top-1] = (sexp) i;
stack[top] = (sexp) (ip+4);
stack[top+1] = cp;
top+=2;
bc = procedure_code(tmp);
print_bytecode(bc);
ip = bc->data;
cp = procedure_vars(tmp);
fprintf(stderr, "... calling procedure at %p\ncp: ", ip);
write_sexp(stderr, cp);
fprintf(stderr, "\n");
/* print_stack(stack, top); */
break;
case OP_JUMP_UNLESS:
fprintf(stderr, "JUMP UNLESS, stack top is %d\n", stack[top-1]);
if (stack[--top] == SEXP_FALSE) {
fprintf(stderr, "test passed, jumping to + %d => %d\n", ((signed char*)ip)[0], ip + ((signed char*)ip)[0]);
ip += ((signed char*)ip)[0];
} else {
fprintf(stderr, "test failed, not jumping\n");
ip++;
}
break;
case OP_JUMP:
fprintf(stderr, "jumping to + %d => %d\n", ((signed char*)ip)[0], ip + ((signed char*)ip)[0]);
ip += ((signed char*)ip)[0];
break;
case OP_RET:
fprintf(stderr, "returning @ %d: ", top-1);
fflush(stderr);
write_sexp(stderr, stack[top-1]);
fprintf(stderr, "...\n");
print_stack(stack, top);
/* top-1 */
/* stack: args ... n ip result */
cp = stack[top-2];
fprintf(stderr, "1\n");
ip = (unsigned char*) stack[top-3];
fprintf(stderr, "2\n");
i = unbox_integer(stack[top-4]);
fprintf(stderr, "3 (i=%d)\n", i);
stack[top-i-4] = stack[top-1];
fprintf(stderr, "4\n");
top = top-i-3;
fprintf(stderr, "... done returning\n");
break;
case OP_DONE:
fprintf(stderr, "finally returning @ %d: ", top-1);
fflush(stderr);
write_sexp(stderr, stack[top-1]);
fprintf(stderr, "\n");
goto end_loop;
default:
fprintf(stderr, "unknown opcode: %d\n", *(ip-1));
stack[top] = SEXP_ERROR;
goto end_loop;
}
fprintf(stderr, "looping\n");
goto loop;
end_loop:
return stack[top-1];
}
/************************** eval interface ****************************/
sexp eval_in_stack(sexp obj, env e, sexp* stack, unsigned int top) {
bytecode bc = compile(SEXP_NULL, cons(obj, SEXP_NULL), e, SEXP_NULL, SEXP_NULL, 1);
fprintf(stderr, "evaling\n");
return vm(bc, e, stack, top);
}
sexp eval(sexp obj, env e) {
sexp* stack = (sexp*) SEXP_ALLOC(sizeof(sexp) * INIT_STACK_SIZE);
sexp res = eval_in_stack(obj, e, stack, 0);
SEXP_FREE(stack);
return res;
}
int main (int argc, char **argv) {
sexp obj, res, *stack;
env e;
sexp_init();
e = make_standard_env();
stack = (sexp*) SEXP_ALLOC(sizeof(sexp) * INIT_STACK_SIZE);
/* repl */
fprintf(stdout, "> ");
fflush(stdout);
while ((obj = read_sexp(stdin)) != SEXP_EOF) {
write_sexp(stdout, obj);
fprintf(stdout, "\n => ");
res = eval_in_stack(obj, e, stack, 0);
write_sexp(stdout, res);
fprintf(stdout, "\n> ");
fflush(stdout);
}
return 0;
}
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