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authorKim Alvefur <zash@zash.se>2019-01-04 08:46:26 +0100
committerKim Alvefur <zash@zash.se>2019-01-04 08:46:26 +0100
commit994f59501b9eecf736792d256434ceb7d519adc7 (patch)
treef50a7955192681d6e54589b128dcdfcfd0561f27 /util/human/units.lua
parent1f80e42aa5522074c5fa09333307a1c3ce50dc58 (diff)
downloadprosody-994f59501b9eecf736792d256434ceb7d519adc7.tar.gz
prosody-994f59501b9eecf736792d256434ceb7d519adc7.zip
util.human.units: A library for formatting numbers with SI units
Diffstat (limited to 'util/human/units.lua')
-rw-r--r--util/human/units.lua58
1 files changed, 58 insertions, 0 deletions
diff --git a/util/human/units.lua b/util/human/units.lua
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index 00000000..2c4662cd
--- /dev/null
+++ b/util/human/units.lua
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+local large = {
+ "k", 1000,
+ "M", 1000000,
+ "G", 1000000000,
+ "T", 1000000000000,
+ "P", 1000000000000000,
+ "E", 1000000000000000000,
+ "Z", 1000000000000000000000,
+ "Y", 1000000000000000000000000,
+}
+local small = {
+ "m", 0.001,
+ "μ", 0.000001,
+ "n", 0.000000001,
+ "p", 0.000000000001,
+ "f", 0.000000000000001,
+ "a", 0.000000000000000001,
+ "z", 0.000000000000000000001,
+ "y", 0.000000000000000000000001,
+}
+
+local binary = {
+ "Ki", 2^10,
+ "Mi", 2^20,
+ "Gi", 2^30,
+ "Ti", 2^40,
+ "Pi", 2^50,
+ "Ei", 2^60,
+ "Zi", 2^70,
+ "Yi", 2^80,
+}
+
+-- n: number, the number to format
+-- unit: string, the base unit
+-- b: optional enum 'b', thousands base
+local function format(n, unit, b) --> string
+ local round = math.floor;
+ local prefixes = large;
+ local logbase = 1000;
+ local fmt = "%.3g %s%s";
+ if n == 0 then
+ return fmt:format(n, "", unit);
+ end
+ if b == 'b' then
+ prefixes = binary;
+ logbase = 1024;
+ elseif n < 1 then
+ prefixes = small;
+ round = math.ceil;
+ end
+ local m = math.max(0, math.min(8, round(math.abs(math.log(math.abs(n), logbase)))));
+ local prefix, multiplier = table.unpack(prefixes, m * 2-1, m*2);
+ return fmt:format(n / (multiplier or 1), prefix or "", unit);
+end
+
+return {
+ format = format;
+};