missing RETLW in a function

[jbmiller]

Okay, I'm NOT a great C programmer but always muddle through ..until now.. I have 3 very similar functions( wait for the desired logic level on a pin, then return). Two compile fine, the third NEVER has the RETLW code! Even if I rearrange the order of the functions, the 'waithd' NEVER gets the RETLW code on the end.

source code....

void waithd() { // waithd
while(!input(pin_b1)){ // wait for high clock
} //
} //

void waitlc() { // waitlc
while(input(pin_b0)){ // wait for low clock
} //
} //



void waithc() { //waithc
while(!input(pin_b0)){ //wait for high clock
} //
} //



listing code.......
0000 00407 .................... void waithd() { // waithd
0000 00408 .................... while(!input(pin_b1)){ // wait for high clock
04AD 1683 00409 BSF 03,5
04AE 1486 00410 BSF 06,1
04AF 1283 00411 BCF 03,5
04B0 1C86 00412 BTFSS 06,1
04B1 2CAD 00413 GOTO 4AD
0000 00414 .................... } //
0000 00415 .................... } //
0000 00416 ....................
0000 00417 .................... void waitlc() { // waitlc
0000 00418 .................... while(input(pin_b0)){ // wait for low clock
04A3 1683 00419 BSF 03,5
04A4 1406 00420 BSF 06,0
04A5 1283 00421 BCF 03,5
04A6 1806 00422 BTFSC 06,0
04A7 2CA3 00423 GOTO 4A3
0000 00424 .................... } //
04A8 3400 00425 RETLW 00
0000 00426 .................... } //
0000 00427 ....................
0000 00428 ....................
0000 00429 ....................
0000 00430 .................... void waithc() { //waithc
0000 00431 .................... while(!input(pin_b0)){ //wait for high clock
049D 1683 00432 BSF 03,5
049E 1406 00433 BSF 06,0
049F 1283 00434 BCF 03,5
04A0 1C06 00435 BTFSS 06,0
04A1 2C9D 00436 GOTO 49D
0000 00437 .................... } //
04A2 3400 00438 RETLW 00
0000 00439 .................... } //


Any idea WHY this occours? No errors on the compile, rest of code is ok.

Thanks Jay

[rnielsen]

I believe that if the function is only called from one place that it will have a GOTO at the end. If it is called from multiple places, in your code, then it will have a RETLW. Try calling the third function from a second location and see if it changes things.

Ronald

[kevcon]

What code comes after this block?

I think you'll find a RETLW is not needed because the waithd function ends at address 04B1 and there is probably another instruction right after it.

[JAY B MILLER]

Oops forgot that the listing isn't linear,following the memory.Thanks for the pointers about this.Used MSDOS 'sort' program to make things easier for me to read and follow. Crazy part is that the machine code version works fine(program diddles the PS2 KBD LEDS) and no amount of coaxing a C program will work.FAST_IO,embedding working asm code with #asm..#endasm. Very frustrating to say the leastAlmost as much 'fun' as the Microchip '24/7 tech support'.
However I do have patience and will eventually get C to control the LEDs.
Thanks for your support guys.
Jay