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#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "vm.h"
#include "ast.h"
#include "read.h"
#include "state.h"
static size_t placeholder(State *S, Chunk *ch) {
size_t old_ix = ch->bc.len;
chunk_wbc(S, ch, 0x00);
chunk_wbc(S, ch, 0x00);
return old_ix;
}
static void patch(State *S, Chunk *ch, size_t addr, uint16_t val) {
ch->bc.d[addr] = val & 0xff;
ch->bc.d[addr+1] = (val & 0xff00) >> 8;
}
static void compile_node(State *S, Chunk *ch, AstNode a) {
switch (a.ty) {
case AST_IDENT:;
char *ident = a.as.str;
if (0 == strcmp(ident, "true")) chunk_wbc(S, ch, OP_TRUE);
else if (0 == strcmp(ident, "false")) chunk_wbc(S, ch, OP_FALSE);
else if (0 == strcmp(ident, "nil")) chunk_wbc(S, ch, OP_NIL);
else {
// global read
ObjString *o = objstring_copy_cstr(S, a.as.str);
chunk_wbc(S, ch, OP_GETGLOBAL);
chunk_wbc(S, ch, chunk_wconst(S, ch, VAL_OBJ(o)));
}
break;
case AST_NUM:
chunk_wbc(S, ch, OP_LOADK);
chunk_wbc(S, ch, chunk_wconst(S, ch, VAL_NUM(a.as.num)));
break;
case AST_STRING: {
ObjString *o = objstring_copy_cstr(S, a.as.str);
chunk_wbc(S, ch, OP_LOADK);
chunk_wbc(S, ch, chunk_wconst(S, ch, VAL_OBJ(o)));
break;
}
case AST_LIST: {
AstVec l = a.as.list;
#define CK(cond, msg) if (!(cond)) { fputs(msg "\n", stderr); exit(1); }
CK(l.len > 0, "can't handle empty list");
CK(l.vals[0].ty == AST_IDENT, "can only call ops");
char *name = l.vals[0].as.str;
if (0 == strcmp(name, "puts")) {
CK(l.len == 2, "puts requires exactly 1 argument");
compile_node(S, ch, l.vals[1]);
chunk_wbc(S, ch, OP_PUTS);
} else if (0 == strcmp(name, "set")) {
CK(l.len == 3, "set requires exactly 2 arguments");
AstNode ident = l.vals[1];
CK(ident.ty == AST_IDENT, "set's first argument must be identifier");
ObjString *o = objstring_copy_cstr(S, ident.as.str);
compile_node(S, ch, l.vals[2]);
chunk_wbc(S, ch, OP_SETGLOBAL);
chunk_wbc(S, ch, chunk_wconst(S, ch, VAL_OBJ(o)));
} else if (0 == strcmp(name, "do")) {
for (int i = 1; i < l.len - 1; i++) {
compile_node(S, ch, l.vals[i]);
chunk_wbc(S, ch, OP_DROP);
}
compile_node(S, ch, l.vals[l.len - 1]);
} else if (0 == strcmp(name, "if")) {
CK(l.len == 4, "if requires exactly 3 arguments");
// (if cond if-true if-false)
// cond
// 0branch ->A
// if-true
// skip ->B
// A: if-false
// B:
compile_node(S, ch, l.vals[1]);
chunk_wbc(S, ch, OP_0BRANCH);
size_t ph_a = placeholder(S, ch);
compile_node(S, ch, l.vals[2]);
chunk_wbc(S, ch, OP_SKIP);
size_t ph_b = placeholder(S, ch);
size_t dest_a = ch->bc.len;
compile_node(S, ch, l.vals[3]);
size_t dest_b = ch->bc.len;
patch(S, ch, ph_a, dest_a - ph_a - 2);
patch(S, ch, ph_b, dest_b - ph_b - 2);
} else if (0 == strcmp(name, "while")) {
CK(l.len >= 3, "while requires at least 2 arguments");
// (while cond body ...)
// A:
// cond
// 0branch ->B
// body ....
// redo ->A
// B:
// nil (while loop always returns nil)
size_t dest_a = ch->bc.len;
compile_node(S, ch, l.vals[1]);
chunk_wbc(S, ch, OP_0BRANCH);
size_t ph_b = placeholder(S, ch);
for (int i = 2; i < l.len; i++) {
compile_node(S, ch, l.vals[i]);
chunk_wbc(S, ch, OP_DROP);
}
chunk_wbc(S, ch, OP_REDO);
size_t ph_a = placeholder(S, ch);
size_t dest_b = ch->bc.len;
chunk_wbc(S, ch, OP_NIL);
patch(S, ch, ph_a, ph_a - dest_a + 2);
patch(S, ch, ph_b, dest_b - ph_b - 2);
} else {
CK(l.len == 3, "can only compile binary ops");
char opchar = l.vals[0].as.str[0];
Op op;
switch (opchar) {
#define OP(char, code) case char: op = code; break;
OP('+', OP_ADD)
OP('-', OP_SUB)
OP('*', OP_MUL)
OP('/', OP_DIV)
OP('=', OP_EQU)
OP('<', OP_CMP)
OP('%', OP_MOD)
#undef OP
default:
printf("unkown op %s\n",l.vals[0].as.str);
exit(1);
break;
}
compile_node(S, ch, l.vals[1]);
compile_node(S, ch, l.vals[2]);
chunk_wbc(S, ch, op);
}
#undef CK
}
}
}
int main(int argc, char **argv) {
State st = state_new();
State *S = &st;
Thread th = thread_new(S);
st.th = &th;
Chunk ch = chunk_new(S);
th.ch = &ch;
S->do_disasm = (argc > 1 && 0 == strcmp(argv[1], "-l"));
char n1[] = "foo";
char n2[] = "bar";
char n3[] = "baz";
ObjString *o1 = objstring_copy_cstr(S, n1);
ObjString *o2 = objstring_copy_cstr(S, n2);
ObjString *o3 = objstring_copy_cstr(S, n3);
ht_put(S, &st.globals, o1, VAL_NUM(69));
ht_put(S, &st.globals, o2, VAL_NUM(2));
ht_put(S, &st.globals, o3, VAL_NUM(3));
AstNode an = read();
compile_node(S, &ch, an);
chunk_wbc(S, &ch, OP_PUTS);
chunk_wbc(S, &ch, OP_RET);
return runvm(S);
}
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