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#ifndef BDL_VM_H
#define BDL_VM_H
#include "types.h"
#include "errors.h"
#include "chunk.h"
#include "ops.h"
#include "debug.h"
#define VM_STACK_CAP 1024
typedef struct VM {
// Program code.
Chunk *chunk;
// Program counter.
u8 *pc;
// Stack.
Object *stack;
} VM;
void vm_init(VM *vm);
void vm_free(VM *vm);
void vm_reset(VM *vm);
void vm_interpret(VM *vm, Chunk *chunk);
void
vm_init(VM *vm) {
*vm = (VM){0};
array_init(vm->stack, VM_STACK_CAP);
}
void
vm_free(VM *vm) {
array_free(vm->stack);
}
void
vm_reset(VM *vm) {
vm_free(vm);
vm_init(vm);
}
// Helper macros for a more clear VM switch.
#define WRONG_ARG_ERR() \
error_push((Error){ \
.type = ERR_TYPE_RUNTIME, \
.value = ERR_WRONG_ARG_TYPE, \
.line = vm->chunk->lines[vm->pc - vm->chunk->code - 1].line, \
.col = vm->chunk->lines[vm->pc - vm->chunk->code - 1].col, \
})
#define FIXNUM_ARITHMETIC_OP(OP) \
do { \
ssize_t n = AS_FIXNUM(array_pop(vm->stack)); \
size_t stack_size = array_size(vm->stack) - n; \
Object obj = array_peek(vm->stack, n - 1); \
if (!IS_FIXNUM(obj)) { \
WRONG_ARG_ERR(); \
return; \
} \
ssize_t acc = AS_FIXNUM(obj); \
while (n > 1) { \
obj = array_peek(vm->stack, n - 2); \
if (!IS_FIXNUM(obj)) { \
WRONG_ARG_ERR(); \
return; \
} \
ssize_t current = AS_FIXNUM(obj); \
acc = acc OP current; \
n--; \
} \
array_head(vm->stack)->size = stack_size; \
array_push(vm->stack, FIXNUM_VAL(acc)); \
} while (false)
#define FIXNUM_COMPARE_OP(OP) \
do { \
ssize_t n = AS_FIXNUM(array_pop(vm->stack)); \
size_t stack_size = array_size(vm->stack) - n; \
Object obj = array_peek(vm->stack, n - 1); \
if (!IS_FIXNUM(obj)) { \
WRONG_ARG_ERR(); \
return; \
} \
ssize_t prev = AS_FIXNUM(obj); \
bool ret = true; \
while (n > 1) { \
obj = array_peek(vm->stack, n - 2); \
if (!IS_FIXNUM(obj)) { \
WRONG_ARG_ERR(); \
return; \
} \
ssize_t current = AS_FIXNUM(obj); \
ret = ret && (prev OP current); \
prev = current; \
n--; \
} \
array_head(vm->stack)->size = stack_size; \
array_push(vm->stack, BOOL_VAL(ret)); \
} while (false)
#define LOGIC_OP(OP) \
do { \
Object a = array_pop(vm->stack); \
Object b = array_pop(vm->stack); \
bool x = IS_TRUE(a); \
bool y = IS_TRUE(b); \
Object result = y OP x ? TRUE_VAL : FALSE_VAL; \
array_push(vm->stack, result); \
} while (false)
void
vm_interpret(VM *vm, Chunk *chunk) {
vm->chunk = chunk;
vm->pc = vm->chunk->code;
if (vm->chunk->code == NULL || array_size(vm->chunk->code) == 0) {
error_push((Error){
.type = ERR_TYPE_RUNTIME,
.value = ERR_EMPTY_CHUNK,
});
return;
}
u8 *last = vm->chunk->code + array_size(vm->chunk->code);
while (vm->pc < last) {
#ifdef DEBUG_TRACE_EXECUTION
printf("stack: [ ");
for (size_t i = 0; i < array_size(vm->stack); i++) {
display(vm->stack[i]);
if (i < array_size(vm->stack) - 1) {
printf(" | ");
}
}
printf(" ]\nop: ");
disassemble_instruction(vm->chunk, (vm->pc - vm->chunk->code));
#endif
u8 instruction = *vm->pc++;
switch (instruction) {
case OP_CONSTANT: {
u8 constant = *vm->pc++;
Object obj = vm->chunk->constants[constant];
array_push(vm->stack, obj);
} break;
case OP_SUM: { FIXNUM_ARITHMETIC_OP(+); } break;
case OP_SUB: { FIXNUM_ARITHMETIC_OP(-); } break;
case OP_MUL: { FIXNUM_ARITHMETIC_OP(*); } break;
case OP_DIV: { FIXNUM_ARITHMETIC_OP(/); } break;
case OP_MOD: { FIXNUM_ARITHMETIC_OP(%); } break;
case OP_NOT: {
Object prev = array_pop(vm->stack);
Object new = IS_TRUE(prev) ? FALSE_VAL : TRUE_VAL;
array_push(vm->stack, new);
} break;
case OP_AND: { LOGIC_OP(&&); } break;
case OP_OR: { LOGIC_OP(||); } break;
case OP_EQUAL: { FIXNUM_COMPARE_OP(==); } break;
case OP_LESS: { FIXNUM_COMPARE_OP(<); } break;
case OP_GREATER: { FIXNUM_COMPARE_OP(>); } break;
case OP_LESS_EQUAL: { FIXNUM_COMPARE_OP(<=); } break;
case OP_GREATER_EQUAL: { FIXNUM_COMPARE_OP(>=); } break;
case OP_RETURN: {
display(array_pop(vm->stack));
printf("\n");
return;
} break;
default: {
error_push((Error){
.type = ERR_TYPE_RUNTIME,
.value = ERR_NOT_IMPLEMENTED,
.line = vm->chunk->lines[vm->pc - vm->chunk->code - 1].line,
.col = vm->chunk->lines[vm->pc - vm->chunk->code - 1].col,
});
return;
} break;
}
}
error_push((Error){
.type = ERR_TYPE_RUNTIME,
.value = ERR_PC_OOB,
.line = vm->chunk->lines[0].line,
.col = vm->chunk->lines[0].col,
});
}
#undef FIXNUM_ARITHMETIC_OP
#undef FIXNUM_COMPARE_OP
#undef LOGIC_OP
#endif // BDL_VM_H
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