libluna: Add more options to to_dynamic_unit()

Also, make the output look more like how it is on linux.

apps/ls.cpp

@@ -63,6 +63,7 @@ Result<int> luna_main(int argc, char** argv)
     bool show_almost_all { false };
     bool long_list { false };
     bool human_readable { false };
+    bool si { false };
 
     os::ArgumentParser parser;
     parser.add_description("List files contained in a directory (defaults to '.', the current directory)"_sv);
@@ -73,6 +74,7 @@ Result<int> luna_main(int argc, char** argv)
     parser.add_switch_argument(long_list, 'l', ""_sv, "use a long listing format"_sv);
     parser.add_switch_argument(human_readable, 'h', "human-readable"_sv,
                                "with -l, show human-readable sizes e.g. 2KiB, 6GiB"_sv);
+    parser.add_switch_argument(si, ' ', "si"_sv, "same as -h, but show sizes in powers of 10"_sv);
     parser.parse(argc, argv);
 
     Vector<String> files;
@@ -116,15 +118,15 @@ Result<int> luna_main(int argc, char** argv)
 
             TRY(find_user_and_group(st, owner, group));
 
-            if (!human_readable)
+            if (!human_readable && !si)
             {
                 os::println("%6o %u %4s %4s %10lu %s", st.st_mode, st.st_nlink, owner.chars(), group.chars(),
                             st.st_size, file.chars());
             }
             else
             {
-                auto size = TRY(to_dynamic_unit(st.st_size));
-                os::println("%6o %u %4s %4s %10s %s", st.st_mode, st.st_nlink, owner.chars(), group.chars(),
+                auto size = TRY(to_dynamic_unit(st.st_size, 10, false, si ? Unit::SI : Unit::Binary, false));
+                os::println("%6o %u %4s %4s %6s %s", st.st_mode, st.st_nlink, owner.chars(), group.chars(),
                             size.chars(), file.chars());
             }
         }

libluna/include/luna/Units.h

@@ -2,4 +2,11 @@
 #include <luna/Result.h>
 #include <luna/String.h>
 
-Result<String> to_dynamic_unit(usize value);
+enum class Unit : usize
+{
+    SI = 1000,
+    Binary = 1024
+};
+
+Result<String> to_dynamic_unit(usize value, usize round_after = 1000, bool separate = true, Unit unit = Unit::Binary,
+                               bool display_unit = true);

libluna/src/Units.cpp

@@ -1,18 +1,44 @@
 #include <luna/Alloc.h>
+#include <luna/CType.h>
 #include <luna/Result.h>
 #include <luna/ScopeGuard.h>
 #include <luna/Units.h>
 
-Result<String> to_dynamic_unit(usize value)
+Result<String> to_dynamic_unit(usize value, usize round_after, bool separate, Unit unit, bool display_unit)
 {
-    if (value < 1024) { return String::format("%zu bytes"_sv, value); }
+    const usize multiplier = (usize)unit;
+    if (value < multiplier) { return String::format("%zu%s"_sv, value, display_unit ? " bytes" : ""); }
+
+    bool si = unit == Unit::SI;
 
     const char* unit_prefixes = "KMGTPE";
-    while (value > (1024 * 1024))
+    if (si) unit_prefixes = "kMGTPE";
+    while (value > (multiplier * multiplier))
     {
-        value /= 1024;
+        value /= multiplier;
         unit_prefixes++;
     }
 
-    return String::format("%zu.%zu %ciB"_sv, value / 1024, (value % 1024) / 103, *unit_prefixes);
+    const usize divider = (si ? 100 : 103);
+
+    usize fixed = value / multiplier;
+    usize rest = (value % multiplier) / divider;
+    bool round = fixed >= round_after;
+
+    if (round)
+    {
+        if (value % multiplier) fixed++;
+        return String::format("%zu%s%c%s"_sv, fixed, separate ? " " : "", *unit_prefixes,
+                              display_unit ? (si ? "B" : "iB") : "");
+    }
+
+    if ((value % multiplier) % divider) rest++;
+    if (rest > 9)
+    {
+        rest = 0;
+        fixed++;
+    }
+
+    return String::format("%zu.%zu%s%c%s"_sv, fixed, rest, separate ? " " : "", *unit_prefixes,
+                          display_unit ? (si ? "B" : "iB") : "");
 }