Libjpeg

JCOEF is a short, it can be changed to an int for a speed increase.

JCOEFPTR is "JCOEF FAR *" (currently a short *).

JSAMPLE is unsigned char

JSAMPROW is "JSAMPLE FAR *" (pointer to one image row of pixel samples)

inptr is is JCOEFPTR, but it would probably be faster as an int ptr.

quantptr is an int32* or a uint32* (probably an int32* since imul is used)

DEQUANTIZE appears to do nothing more than multiply.