Port bit linearity.

Been writing some code for usb oscilloscope using pic32mx274.
Using an external a2d which is 10 bits.
Sadly I cant use portb 0-9 linearly.
Some of the port bits are used by usb.
So ended up with  a mess of code to read the port and slow as well.

unsigned short reada2dright()
{ 
 unsigned short ax;
 unsigned short bx;
 ax=PORTB;
 bx=ax&0x1f;
 
 if (ax&sb7)
 bx=bx+sb5;
 
 if (ax&sb8)
 bx=bx+sb6;
 
 if (ax&sb9)
 bx=bx+sb7;
 
 if (ax&sb13)
 bx=bx+sb8;
 
 if (ax&sb15)
 bx=bx+sb9;
 
 
 return bx;
}

ric
How are the "sb##" values defined ?

sb0 =1
sb1=2
sb2=4
sb3=8 etc bit set for power of 2.
sb4=16

and also change

bx=bx+sb5;

to

bx |= sb5;

I would change the PCB to do the bit swapping :)
 

if (ax&sb7)
 bx=bx+sb5;
 
 if (ax&sb8)
 bx=bx+sb6;
 
 if (ax&sb9)
 bx=bx+sb7;

could be

ax = ax>>2;
bx = bx | (ax & 0xe0);

Thanks that looks about shortest.
 

If you call that function at only one place, and with high frequency, then consider to define that function as static inline uint16_t ChkPortBits(void), to get rid of the function call overhead.