[checksum] more load balancing optimizations

* SetChecksumAffinity() now spreads the affinity evenly between cores
* Also increase the read buffer size to help with performance
* At this stage, the only limiting factor regarding performance seems
  to be the speed of the SHA-256 algorithm...

src/stdio.c

@@ -74,6 +74,34 @@ void _uprintf(const char *format, ...)
 }
 #endif
 
+// Prints a bitstring of a number of any size, with or without leading zeroes.
+// See also the printbits() and printbitslz() helper macros in rufus.h
+char *_printbits(size_t const size, void const * const ptr, int leading_zeroes)
+{
+	// sizeof(uintmax_t) so that we have enough space to store whatever is thrown at us
+	static char str[sizeof(uintmax_t) * 8 + 3];
+	size_t i;
+	uint8_t* b = (uint8_t*)ptr;
+	uintmax_t mask, lzmask = 0, val = 0;
+
+	// Little endian, the SCOURGE of any rational computing
+	for (i = 0; i < size; i++)
+		val |= ((uintmax_t)b[i]) << (8 * i);
+
+	str[0] = '0';
+	str[1] = 'b';
+	if (leading_zeroes)
+		lzmask = 1ULL << (size * 8 - 1);
+	for (i = 2, mask = 1ULL << (sizeof(uintmax_t) * 8 - 1); mask != 0; mask >>= 1) {
+		if ((i > 2) || (lzmask & mask))
+			str[i++] = (val & mask) ? '1' : '0';
+		else if (val & mask)
+			str[i++] = '1';
+	}
+	str[i] = '\0';
+	return str;
+}
+
 void DumpBufferHex(void *buf, size_t size)
 {
 	unsigned char* buffer = (unsigned char*)buf;