Halve caster's HP upon Skill activation

[raksone 0]

Hello guys!

  I've been trying to get the topic's title result but I have failed in all my attempts.

 

I want the skill to reduce the caster's HP to half upon activation, and then I will continue adding new skill effects, but I can't get to the first result.

 

This is how I go so far:

 

case AC_SACRIFICEPOWER:
	{
			int hp = sstatus->max_hp;
				hp = hp*50/100;
			status_zap(src, hp, 0);
	}
break;

But, it is not working as intended. Is not halving my HP at all... Just reducing it for x rate... or even killing my character when full HP.

Any ideas?