Use std::popcount further.

Analyser/Static/StaticAnalyser.cpp

@@ -9,6 +9,7 @@
 #include "StaticAnalyser.hpp"
 
 #include <algorithm>
+#include <bit>
 #include <cstddef>
 #include <cstdlib>
 #include <cstring>
@@ -340,13 +341,7 @@ TargetList Analyser::Static::GetTargets(const std::string &file_name) {
 	TargetPlatform::IntType potential_platforms = 0;
 	Media media = GetMediaAndPlatforms(file_name, potential_platforms);
 
-	// TODO: std::popcount here.
-	int total_options = 0;
-	TargetPlatform::IntType mask = 1;
-	while(mask) {
-		total_options += bool(potential_platforms & mask);
-		mask <<= 1;
-	}
+	int total_options = std::popcount(potential_platforms);
 	const bool is_confident = total_options == 1;
 	// i.e. This analyser `is_confident` if file analysis suggested only one potential target platform.
 	// The machine-specific static analyser will still run in case it can provide meaningful annotations on

Components/DiskII/DiskII.cpp

@@ -8,6 +8,7 @@
 
 #include "DiskII.hpp"
 
+#include <bit>
 #include <cstdio>
 #include <cstring>
 
@@ -62,11 +63,7 @@ void DiskII::set_control(const Control control, const bool on) {
 		if(stepper_mask_&4) direction += (((stepper_position_ - 4) + 4)&7) - 4;
 		if(stepper_mask_&8) direction += (((stepper_position_ - 6) + 4)&7) - 4;
 
-		// TODO: when adopting C++20, replace with std::popcount.
-		int bits_set = stepper_mask_;
-		bits_set = (bits_set & 0x5) + ((bits_set >> 1) & 0x5);
-		bits_set = (bits_set & 0x3) + ((bits_set >> 2) & 0x3);
-
+		const int bits_set = std::popcount(uint8_t(stepper_mask_));
 		direction /= bits_set;
 
 		// Compare to the stepper position to decide whether that pulls in the current cog notch,