Toggling Port0 may not be fruitful as it looks like it's used as the bus for the flash rom - the processor hardware may have other ideas. Best to try Port1.

something like:

P1_0 = 1; //to set the port bit - setb P1.0 in asm

P1_0 = 0; //to reset the port bit - clr P1.0 in asm

The compiler 'knows' about bits and the above code ends up being one instruction for each of the operations.

Also, just a little nit pick - to decrement a variable, use:
val--; rather than val -=1; same diff, but comes down to convention.

Another thing: for variables, try to use 'char' where possible as this is an 8bit processor.