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db_vmint.c
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db_vmint.c
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/* db_vmint.c - bytecode interpreter for a simple virtual machine
*
* Copyright (c) 2009-2012 by David Michael Betz. All rights reserved.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <ctype.h>
#include "db_vm.h"
/* prototypes for local functions */
static void StartCode(Interpreter *i);
static void PopFrame(Interpreter *i);
static void StringCat(Interpreter *i);
static void AfterCompact(void *cookie);
/* Execute - execute the main code */
int Execute(System *sys, ObjHeap *heap, VMHANDLE main)
{
size_t stackSize;
Interpreter *i;
VMVALUE tmp, tmp2, ind;
VMHANDLE obj, htmp;
int8_t tmpb;
/* allocate the interpreter state */
if (!(i = (Interpreter *)AllocateFreeSpace(sys, sizeof(Interpreter))))
return VMFALSE;
/* make sure there is space left for the stack */
if ((stackSize = (sys->freeTop - sys->freeNext) / sizeof(VMVALUE)) <= 0)
return VMFALSE;
/* setup the heap before/after compact functions */
heap->beforeCompact = NULL;
heap->afterCompact = AfterCompact;
heap->compactCookie = i;
/* initialize the interpreter state */
i->sys = sys;
i->heap = heap;
i->stack = (VMVALUE *)((uint8_t *)i + sizeof(Interpreter));
i->stackTop = i->stack + stackSize;
/* setup to execute the main function */
i->code = main;
ObjAddRef(i->code);
i->cbase = i->pc = GetCodePtr(main);
i->sp = i->fp = i->stackTop;
i->hsp = i->hfp = (VMHANDLE *)i->stack - 1;
if (setjmp(i->sys->errorTarget)) {
while (i->hsp > (VMHANDLE *)i->stack)
ObjRelease(i->heap, PopH(i));
ObjRelease(i->heap, i->code);
return VMFALSE;
}
for (;;) {
#if 0
ShowStack(i);
DecodeInstruction(0, 0, i->pc);
#endif
switch (VMCODEBYTE(i->pc++)) {
case OP_HALT:
return VMTRUE;
case OP_BRT:
get_VMVALUE(tmp, VMCODEBYTE(i->pc++));
if (Pop(i))
i->pc += tmp;
break;
case OP_BRTSC:
get_VMVALUE(tmp, VMCODEBYTE(i->pc++));
if (*i->sp)
i->pc += tmp;
else
Drop(i, 1);
break;
case OP_BRF:
get_VMVALUE(tmp, VMCODEBYTE(i->pc++));
if (!Pop(i))
i->pc += tmp;
break;
case OP_BRFSC:
get_VMVALUE(tmp, VMCODEBYTE(i->pc++));
if (!*i->sp)
i->pc += tmp;
else
Drop(i, 1);
break;
case OP_BR:
get_VMVALUE(tmp, VMCODEBYTE(i->pc++));
i->pc += tmp;
break;
case OP_NOT:
*i->sp = (*i->sp ? VMFALSE : VMTRUE);
break;
case OP_NEG:
*i->sp = -*i->sp;
break;
case OP_ADD:
tmp = Pop(i);
*i->sp += tmp;
break;
case OP_SUB:
tmp = Pop(i);
*i->sp -= tmp;
break;
case OP_MUL:
tmp = Pop(i);
*i->sp *= tmp;
break;
case OP_DIV:
tmp = Pop(i);
*i->sp = (tmp == 0 ? 0 : *i->sp / tmp);
break;
case OP_REM:
tmp = Pop(i);
*i->sp = (tmp == 0 ? 0 : *i->sp % tmp);
break;
case OP_CAT:
StringCat(i);
break;
case OP_BNOT:
*i->sp = ~*i->sp;
break;
case OP_BAND:
tmp = Pop(i);
*i->sp &= tmp;
break;
case OP_BOR:
tmp = Pop(i);
*i->sp |= tmp;
break;
case OP_BXOR:
tmp = Pop(i);
*i->sp ^= tmp;
break;
case OP_SHL:
tmp = Pop(i);
*i->sp <<= tmp;
break;
case OP_SHR:
tmp = Pop(i);
*i->sp >>= tmp;
break;
case OP_LT:
tmp = Pop(i);
*i->sp = (*i->sp < tmp ? VMTRUE : VMFALSE);
break;
case OP_LE:
tmp = Pop(i);
*i->sp = (*i->sp <= tmp ? VMTRUE : VMFALSE);
break;
case OP_EQ:
tmp = Pop(i);
*i->sp = (*i->sp == tmp ? VMTRUE : VMFALSE);
break;
case OP_NE:
tmp = Pop(i);
*i->sp = (*i->sp != tmp ? VMTRUE : VMFALSE);
break;
case OP_GE:
tmp = Pop(i);
*i->sp = (*i->sp >= tmp ? VMTRUE : VMFALSE);
break;
case OP_GT:
tmp = Pop(i);
*i->sp = (*i->sp > tmp ? VMTRUE : VMFALSE);
break;
case OP_LIT:
get_VMVALUE(tmp, VMCODEBYTE(i->pc++));
CPush(i, tmp);
break;
case OP_GREF:
get_VMVALUE(tmp, VMCODEBYTE(i->pc++));
obj = (VMHANDLE)tmp;
CPush(i, GetSymbolPtr(obj)->v.iValue);
break;
case OP_GSET:
get_VMVALUE(tmp, VMCODEBYTE(i->pc++));
obj = (VMHANDLE)tmp;
GetSymbolPtr(obj)->v.iValue = Pop(i);
break;
case OP_LREF:
tmpb = (int8_t)VMCODEBYTE(i->pc++);
CPush(i, i->fp[(int)tmpb]);
break;
case OP_LSET:
tmpb = (int8_t)VMCODEBYTE(i->pc++);
i->fp[(int)tmpb] = Pop(i);
break;
case OP_VREF:
ind = *i->sp;
obj = *i->hsp;
if (ind < 0 || ind >= GetHeapObjSize(obj))
Abort(i->sys, str_subscript_err, ind);
*i->sp = GetIntegerVectorBase(obj)[ind];
DropH(i, 1);
break;
case OP_VSET:
tmp2 = Pop(i);
ind = Pop(i);
obj = *i->hsp;
if (ind < 0 || ind >= GetHeapObjSize(obj))
Abort(i->sys, str_subscript_err, ind);
GetIntegerVectorBase(obj)[ind] = tmp2;
DropH(i, 1);
break;
case OP_LITH:
get_VMVALUE(tmp, VMCODEBYTE(i->pc++));
CPushH(i, (VMHANDLE)tmp);
ObjAddRef(*i->hsp);
break;
case OP_GREFH:
get_VMVALUE(tmp, VMCODEBYTE(i->pc++));
CPushH(i, GetSymbolPtr((VMHANDLE)tmp)->v.hValue);
ObjAddRef(*i->hsp);
break;
case OP_GSETH:
get_VMVALUE(tmp, VMCODEBYTE(i->pc++));
ObjRelease(i->heap, GetSymbolPtr((VMHANDLE)tmp)->v.hValue);
GetSymbolPtr((VMHANDLE)tmp)->v.hValue = PopH(i);
break;
case OP_LREFH:
tmpb = (int8_t)VMCODEBYTE(i->pc++);
CPushH(i, i->hfp[(int)tmpb]);
ObjAddRef(*i->hsp);
break;
case OP_LSETH:
tmpb = (int8_t)VMCODEBYTE(i->pc++);
ObjRelease(i->heap, i->hfp[(int)tmpb]);
i->hfp[(int)tmpb] = PopH(i);
break;
case OP_VREFH:
ind = Pop(i);
obj = *i->hsp;
if (ind < 0 || ind >= GetHeapObjSize(obj))
Abort(i->sys, str_subscript_err, ind);
*i->hsp = GetStringVectorBase(obj)[ind];
ObjAddRef(*i->hsp);
break;
case OP_VSETH:
htmp = PopH(i);
ind = Pop(i);
obj = *i->hsp;
if (ind < 0 || ind >= GetHeapObjSize(obj))
Abort(i->sys, str_subscript_err, ind);
ObjRelease(i->heap, GetStringVectorBase(obj)[ind]);
GetStringVectorBase(obj)[ind] = htmp;
DropH(i, 1);
break;
case OP_RESERVE:
tmp = VMCODEBYTE(i->pc++);
tmp2 = VMCODEBYTE(i->pc++);
Reserve(i, tmp);
ReserveH(i, tmp2);
break;
case OP_CALL:
StartCode(i);
break;
case OP_RETURN:
tmp = *i->sp;
PopFrame(i);
Push(i, tmp);
break;
case OP_RETURNH:
htmp = *i->hsp;
PopFrame(i);
PushH(i, htmp);
break;
case OP_RETURNV:
PopFrame(i);
break;
case OP_DROP:
Drop(i, 1);
break;
case OP_DROPH:
ObjRelease(i->heap, *i->hsp);
DropH(i, 1);
break;
default:
Abort(i->sys, str_opcode_err, VMCODEBYTE(i->pc - 1));
break;
}
}
}
static void StartCode(Interpreter *i)
{
VMHANDLE code = PopH(i);
VMVALUE tmp, tmp2;
if (!code)
Abort(i->sys, str_not_code_object_err, code);
switch (GetHeapObjType(code)) {
case ObjTypeCode:
tmp = (VMVALUE)(i->fp - i->stack);
tmp2 = (VMVALUE)(i->hfp - (VMHANDLE *)i->stack);
i->hfp = i->hsp;
PushH(i, i->code);
i->fp = i->sp;
Reserve(i, F_SIZE);
i->fp[F_FP] = tmp;
i->fp[F_HFP] = tmp2;
i->fp[F_PC] = (VMVALUE)(i->pc - i->cbase);
i->code = code;
ObjAddRef(i->code);
i->cbase = i->pc = GetCodePtr(code);
break;
case ObjTypeIntrinsic:
(*GetIntrinsicHandler(code))(i);
break;
default:
Abort(i->sys, str_not_code_object_err, code);
break;
}
}
static void PopFrame(Interpreter *i)
{
int argumentCount = VMCODEBYTE(i->pc++);
int handleArgumentCount = VMCODEBYTE(i->pc++);
ObjRelease(i->heap, i->code);
i->code = i->hfp[HF_CODE];
i->hsp = i->hfp;
while (--handleArgumentCount >= 0) {
ObjRelease(i->heap, *i->hsp);
DropH(i, 1);
}
i->cbase = GetCodePtr(i->code);
i->pc = i->cbase + i->fp[F_PC];
i->hfp = (VMHANDLE *)i->stack + i->fp[F_HFP];
i->sp = i->fp;
i->fp = i->stack + i->fp[F_FP];
Drop(i, argumentCount);
}
static void StringCat(Interpreter *i)
{
VMHANDLE hStr2 = PopH(i);
VMHANDLE hStr1 = *i->hsp;
uint8_t *str1, *str2, *str;
size_t len1, len2;
/* get the first string pointer and length */
str1 = GetStringPtr(hStr1);
len1 = GetHeapObjSize(hStr1);
/* get the second string pointer and length */
str2 = GetStringPtr(hStr2);
len2 = GetHeapObjSize(hStr2);
/* allocate the result string */
if (!(*i->hsp = NewString(i->heap, len1 + len2)))
Abort(i->sys, "insufficient memory");
str = GetStringPtr(*i->hsp);
/* copy the source strings into the result string */
memcpy(str, str1, len1);
memcpy(str + len1, str2, len2);
/* release the two argument strings */
ObjRelease(i->heap, hStr1);
ObjRelease(i->heap, hStr2);
}
void ShowStack(Interpreter *i)
{
VMHANDLE *hp;
VMVALUE *p;
for (hp = (VMHANDLE *)i->stack; hp <= i->hsp; ++hp) {
if (hp == i->hfp)
VM_printf(str_hfp_tag);
VM_printf(str_hstack_entry_fmt, (VMUVALUE)*hp);
}
VM_printf(str_stack_separator);
for (p = i->sp; p < i->stackTop; ++p) {
if (p == i->fp)
VM_printf(str_fp_tag);
VM_printf(str_stack_entry, *p);
}
VM_putchar('\n');
}
void StackOverflow(Interpreter *i)
{
Abort(i->sys, str_stack_overflow_err);
}
/* AfterCompact - called after the heap manager compacts the heap */
static void AfterCompact(void *cookie)
{
Interpreter *i = (Interpreter *)cookie;
uint8_t *cbase = GetCodePtr(i->code);
i->pc = cbase + (i->pc - i->cbase);
i->cbase = cbase;
}
FLASH_SPACE char str_subscript_err[] = "subscript out of bounds: %d";
FLASH_SPACE char str_stack_overflow_err[] = "stack overflow";
FLASH_SPACE char str_not_code_object_err[] = "not code object: %d";
FLASH_SPACE char str_opcode_err[] = "undefined opcode 0x%02x";
FLASH_SPACE char str_value_fmt[] = "%d";
FLASH_SPACE char str_hfp_tag[] = " <hfp>";
FLASH_SPACE char str_hstack_entry_fmt[] = " %08x";
FLASH_SPACE char str_stack_separator[] = " ---";
FLASH_SPACE char str_fp_tag[] = " <fp>";
FLASH_SPACE char str_stack_entry[] = " %d";