[Yashas]

Jump Instructions
There are assembly instructions which allow you to jump.

Instruction List & Usage
Here is a list of all of them:

#	mnemonic	operand	semantics
51	JUMP	offset	CIP = CIP + offset (jump to the address relative from the current position)
53	JZER	offset	if PRI == 0 then CIP = CIP + offset
54	JNZ	offset	if PRI != 0 then CIP = CIP + offset
55	JEQ	offset	if PRI == ALT then CIP = CIP + offset
56	JNEQ	offset	if PRI != ALT then CIP = CIP + offset
57	JLESS	offset	if PRI < ALT then CIP = CIP + offset (unsigned)
58	JLEQ	offset	if PRI <= ALT then CIP = CIP + offset (unsigned)
59	JGRTR	offset	if PRI > ALT then CIP = CIP + offset (unsigned)
60	JGEQ	offset	if PRI >= ALT then CIP = CIP + offset (unsigned)
61	JSLESS	offset	if PRI < ALT then CIP = CIP + offset (signed)
62	JSLEQ	offset	if PRI <= ALT then CIP = CIP + offset (signed)
63	JSGRTR	offset	if PRI > ALT then CIP = CIP + offset (signed)
64	JSGEQ	offset	if PRI >= ALT then CIP = CIP + offset (signed)
128	JUMP.pri		CIP = PRI (indirect jump)

The PAWN Implementer Guide says we can pass offsets to the jump instructions but unfortunately passing offsets as numbers crashes the compiler.

Код:

main()
{
     new x,y = 10,z = 50;
     
     #emit LOAD.S.pri y
     #emit LOAD.S.alt z
     #emit JEQ 8

     #emit CONST.pri 100

     #emit STOR.S.pri x
     printf("%d",x);
}

The above code will crash the compiler.

The only way you can now pass offsets to the jump instructions is by using labels.

The following code illustrates how to use labels as offsets for jump instructions

Код:

#include <a_samp>
main()
{
     new y = 10,z = 11;

     print("Checking two numbers for equality");
     goto check;

     not_equal:
     printf("The numbers are not equal");
     return 0;

     equal:
     print("The numbers are equal!");
     return 0;

     check:
     #emit LOAD.S.pri y
     #emit LOAD.S.alt z
     #emit JEQ equal
     #emit JUMP not_equal
}

Using jump instructions in assembly hardly gives you any advantage. It will only improve performance by negligible amount when compared to using "goto label;".

Код:

if(k == 0) goto label;

will produce an assembly output

Код:

#emit LOAD.S.pri k
#emit JZER somewhere

somewhere:
JUMP label

The extra jump can be avoided by manually jumping using assembly

Код:

#emit LOAD.S.pri k
#emit JZER label

Compiler Bug
If you try to compile the following code you will get an error stating that symbol "abc" is undefined even though it is defined.

Код:

goto abc; //No error
#emit LOAD.pri a
#emit LOAD.alt b
#emit JSLESS abc //Error, undefined symbol abc

abc:
your code

The compiler allows you to use goto with lables that are defined later. But unfortunately the compiler does not recognize labels that are defined later when you use #emit.

Bug #13 in Known Runtime/Compiler Bugs topic.