Day 1 part 2

days/1/code.wat

@@ -5,11 +5,10 @@
   (global $inputEnd (mut i32) (i32.const 0))
   (global $outputEnd (mut i32) (i32.const 0))
 
-  (global $currentMaxCals (mut i32) (i32.const 0))
-
   (func (export "part1") (result i32)
+    (local $currentMaxCals i32)
     (local $currentElf i32)
-    ;; Read nput length
+    ;; Read input length
     i32.const 0
     i32.load
 
@@ -23,16 +22,16 @@
     global.set $readLoc
 
     i32.const 0
-    global.set $currentMaxCals
+    local.set $currentMaxCals
 
     loop $readLoop
-      global.get $currentMaxCals
+      local.get $currentMaxCals
       call $readElf
       local.tee $currentElf
       i32.lt_u
       if
         local.get $currentElf
-        global.set $currentMaxCals
+        local.set $currentMaxCals
       end
 
       global.get $readLoc
@@ -48,7 +47,118 @@
     global.set $outputEnd
 
     ;; write the number
-    global.get $currentMaxCals
+    local.get $currentMaxCals
+    call $writeNum
+
+    ;; get the length to return
+    global.get $inputEnd
+    global.get $outputEnd
+    global.get $inputEnd
+    i32.const 4
+    i32.add
+    i32.sub
+    i32.store
+
+    ;; return location of length
+    global.get $inputEnd
+  )
+
+  (func (export "part2") (result i32)
+    (local $currentElf i32)
+    (local $maxCals1 i32)
+    (local $maxCals2 i32)
+    (local $maxCals3 i32)
+    ;; Read input length
+    i32.const 0
+    i32.load
+
+    ;; Store input end byte
+    i32.const 4
+    i32.add
+    global.set $inputEnd
+
+    ;; Set up start read location
+    i32.const 4 ;; first memory address after length u32
+    global.set $readLoc
+
+    i32.const 0
+    local.set $maxCals1
+    i32.const 0
+    local.set $maxCals2
+    i32.const 0
+    local.set $maxCals3
+
+    loop $readLoop
+      call $readElf
+      local.set $currentElf
+
+      block $comparisons
+
+        ;; compare with stored value 1 (highest)
+        local.get $maxCals1
+        local.get $currentElf
+        i32.lt_u
+        if
+          ;; pick up new max 3 (in order)
+          local.get $maxCals2
+          local.get $maxCals1
+          local.get $currentElf
+
+          local.set $maxCals1
+          local.set $maxCals2
+          local.set $maxCals3
+          br $comparisons
+        end
+
+        ;; compare with stored value 2
+        local.get $maxCals2
+        local.get $currentElf
+        i32.lt_u
+        if
+          ;; pick up new second and third max (in order)
+          local.get $maxCals2
+          local.get $currentElf
+
+          local.set $maxCals2
+          local.set $maxCals3
+          br $comparisons
+        end
+
+        ;; compare with stored value 3
+        local.get $maxCals3
+        local.get $currentElf
+        i32.lt_u
+        if
+          local.get $currentElf
+          local.set $maxCals3
+          br $comparisons
+        end
+
+      end ;; $comparisons
+
+      global.get $readLoc
+      global.get $inputEnd
+      i32.lt_s
+      br_if $readLoop
+    end ;; $readLoop
+
+    ;; add up top 3
+    local.get $maxCals1
+    local.get $maxCals2
+    local.get $maxCals3
+    i32.add
+    i32.add
+    local.set $maxCals1
+
+
+    ;; set up output end pointer
+    global.get $inputEnd
+    i32.const 4
+    i32.add
+    global.set $outputEnd
+
+    ;; write the number
+    local.get $maxCals1
     call $writeNum
 
     ;; get the length to return