fast 0..255 * 0..255 => 0..255 rounded multiplication

if there's a pending marker from the entropy stream, return that otherwise, fetch from the stream and get a marker. if there's no marker, return 0xff,

take a -128..127 value and stbi__clamp it and convert to 0..255

returns 1 if "a*b*c + add" has no negative terms/factors and doesn't overflow

initialize a callback-based context

initialize a memory-decode context

returns 1 if the product is valid, 0 on overflow. negative factors are considered invalid.

clean up the temporary component buffers

decode a jpeg huffman value from the bitstream

after a restart interval, stbi__jpeg_reset the entropy decoder and the dc prediction

initialize a callback-based context

combined JPEG 'receive' and JPEG 'extend', since baseline always extends everything it receives.

returns 0..31 for the highest set bit

mallocs with size overflow checking

extract an arbitrarily-aligned N-bit value (N=bits) from v, and then make it 8-bits long and fractionally extend it to full full range.

returns STBI_rgb or whatever, 0 on error

return 1 if the sum is valid, 0 on overflow. negative terms are considered invalid.

@OPTIMIZE: provide an option that always forces left-predict or paeth predict

returns 1 if the sum of two signed ints is valid (between -2^31 and 2^31-1 inclusive), 0 on overflow.