Fixed num2hex not padding with the right number of zeros (#19881)

code/libs/s_html/hexadecimal.dm

@@ -53,45 +53,32 @@ proc/hex2num(hex)
 
 	return(num)
 
-
-proc/num2hex(num, placeholder=2)
-	//Converts a numeral (eg. 255) into a hexadecimal string (eg. "FF")
-	//The 'placeholder' argument inserts zeroes in front of the string
-	// until the string is that length -- eg. 15 in hexadecimal is "F",
-	// but the placeholder of 2 would make it "0F".
-
+//Returns the hex value of a decimal number
+//len == length of returned string
+//if len < 0 then the returned string will be as long as it needs to be to contain the data
+//Only supports positive numbers
+//if an invalid number is provided, it assumes num==0
+/proc/num2hex(var/num, var/len = 2)
 	if(!isnum(num))
-		CRASH("num2hex not given a numeric argument (user error)")
-		return
-
-	if(!num)
-		return("0") //no computation necessary
-
-	var/hex = ""
-
-	var/i = 0
-	while(16**i < num) i++
-
-	for(var/power = i-1, power >= 0, power--)
-		var/val = round( num / (16 ** power) )
-		num -= val * (16 ** power)
-		switch(val)
-			if(0,1,2,3,4,5,6,7,8,9)
-				hex += "[val]"
-
-			if(10)
-				hex += "A"
-			if(11)
-				hex += "B"
-			if(12)
-				hex += "C"
-			if(13)
-				hex += "D"
-			if(14)
-				hex += "E"
-			if(15)
-				hex += "F"
-
-	while(lentext(hex) < placeholder) hex = "0[hex]"
-
-	return(hex)
+		num = 0
+	num = round(abs(num))
+	. = ""
+	var/i=0
+	while(1)
+		if(len<=0)
+			if(!num)
+				break
+		else
+			if(i>=len)
+				break
+		var/remainder = num/16
+		num = round(remainder)
+		remainder = (remainder - num) * 16
+		switch(remainder)
+			if(1 to 9)
+				. = "[remainder]" + .
+			if(10 to 15)
+				. = ascii2text(remainder+55) + .
+			else
+				. = "0" + .
+		i++

code/modules/unit_tests/_unit_tests.dm

@@ -2,5 +2,6 @@
 #include "unit_test.dm"
 #include "circuitboards.dm"
 #include "dna_and_disabilities.dm"
+#include "hexadecimal.dm"
 #include "reagent_recipe_collisions.dm"
 #endif

code/modules/unit_tests/hexadecimal.dm

@@ -0,0 +1,21 @@
+/datum/unit_test/num2hex/start()
+	assert_eq(num2hex(0, 1), "0")
+	assert_eq(num2hex(1, 1), "1")
+	assert_eq(num2hex(15, 1), "F")
+	assert_eq(num2hex(16, 1), "0")
+	assert_eq(num2hex(0xABCDE, 1), "E")
+	assert_eq(num2hex(SHORT_REAL_LIMIT-1, 1), "F")
+
+	assert_eq(num2hex(0, 2), "00")
+	assert_eq(num2hex(1, 2), "01")
+	assert_eq(num2hex(15, 2), "0F")
+	assert_eq(num2hex(16, 2), "10")
+	assert_eq(num2hex(0xABCDE, 2), "DE")
+	assert_eq(num2hex(SHORT_REAL_LIMIT-1, 2), "FF")
+
+	assert_eq(num2hex(0, 8), "00000000")
+	assert_eq(num2hex(1, 8), "00000001")
+	assert_eq(num2hex(15, 8), "0000000F")
+	assert_eq(num2hex(16, 8), "00000010")
+	assert_eq(num2hex(0xABCDE, 8), "000ABCDE")
+	assert_eq(num2hex(SHORT_REAL_LIMIT-1, 8), "00FFFFFF")

code/modules/unit_tests/unit_test.dm

@@ -70,3 +70,5 @@ var/failed_any_test = FALSE
 		CHECK_TICK
 
 	del(world)
+
+#define assert_eq(a, b) (a == b || (fail("[__FILE__]:[__LINE__]: assert_eq failed. Expected [b], got [a].")))