OrdinaryMagician/vkdoom_m
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- Use a union, rather than pointer aliasing, to access the parts of a VM instruction.

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SVN r1922 (scripting)
This commit is contained in:
Randy Heit 2009-10-17 00:33:23 +00:00
commit e5ef25591d
10 changed files with 171 additions and 154 deletions
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46
src/zscript/vm.h
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@ -17,7 +17,41 @@ typedef signed int VM_SWORD;
typedef VM_UBYTE VM_ATAG;
#define VM_EPSILON (1/1024.0)
#define VM_OPSIZE 4 // Number of bytes used by one opcode
union VMOP
{
struct
{
VM_UBYTE op, a, b, c;
};
struct
{
VM_SBYTE pad0, as, bs, cs;
};
struct
{
VM_SWORD pad1:8, i24:24;
};
struct
{
VM_SWORD pad2:16, i16:16;
};
struct
{
VM_UHALF pad3, i16u;
};
VM_UWORD word;
// Interesting fact: VC++ produces better code for i16 when it's defined
// as a bitfield than when it's defined as two discrete units.
// Compare:
// mov eax,dword ptr [op] ; As two discrete units
// shr eax,10h
// movsx eax,ax
// versus:
// mov eax,dword ptr [op] ; As a bitfield
// sar eax,10h
};
enum
{
@ -685,7 +719,7 @@ public:
VMScriptFunction();
~VMScriptFunction();
size_t PropagateMark();
VM_UBYTE *AllocCode(int numops);
VMOP *AllocCode(int numops);
int *AllocKonstD(int numkonst);
double *AllocKonstF(int numkonst);
FString *AllocKonstS(int numkonst);
@ -694,13 +728,13 @@ public:
VM_ATAG *KonstATags() { return (VM_UBYTE *)(KonstA + NumKonstA); }
const VM_ATAG *KonstATags() const { return (VM_UBYTE *)(KonstA + NumKonstA); }
VM_UBYTE *Code;
VMOP *Code;
int *KonstD;
double *KonstF;
FString *KonstS;
FVoidObj *KonstA;
int ExtraSpace;
int NumCodeBytes;
int CodeSize; // Size of code in instructions (not bytes)
VM_UBYTE NumRegD;
VM_UBYTE NumRegF;
VM_UBYTE NumRegS;
@ -809,10 +843,10 @@ enum EVMEngine
};
void VMSelectEngine(EVMEngine engine);
extern int (*VMExec)(VMFrameStack *stack, const VM_UBYTE *pc, VMReturn *ret, int numret);
extern int (*VMExec)(VMFrameStack *stack, const VMOP *pc, VMReturn *ret, int numret);
void VMFillParams(VMValue *params, VMFrame *callee, int numparam);
void VMDumpConstants(FILE *out, const VMScriptFunction *func);
void VMDisasm(FILE *out, const VM_UBYTE *code, int codesize, const VMScriptFunction *func);
void VMDisasm(FILE *out, const VMOP *code, int codesize, const VMScriptFunction *func);
#endif