sol.diff

--- cc2/decode_mips.lua 2019-02-27 16:16:48.338797400 +0000
+++ sol/decode_mips.sol 2019-02-27 16:08:40.508730600 +0000
@@ -5,45 +5,51 @@

 local mips_decode = {}

+typedef decode_handler = {
+    shift: int?,
+    mask: int?,
+    table: [function(table, int, int, int, int, int, int) -> bool, string, string?, bool]
+}
+
 local instance = {
-    decode_table = {},
-    gpr_declared = {},
-    gpr_needs_writeback = {},
-    cp0r_declared = {},
-    cp0r_needs_writeback = {},
-    program_counter = 0
+    decode_table = {} : [decode_handler],
+    gpr_declared = {} : [bool],
+    gpr_needs_writeback = {} : [bool],
+    cp0r_declared = {} : [bool],
+    cp0r_needs_writeback = {} : [bool],
+    program_counter = 0 : int
 }

-local function opcode(instruction)
+local function opcode(instruction: int) -> int
     return band(rshift(instruction, 26), 0x3F)
 end

-local function first_source(instruction)
+local function first_source(instruction: int) -> int
     return band(rshift(instruction, 21), 0x1F)
 end

-local function second_source(instruction)
+local function second_source(instruction: int) -> int
     return band(rshift(instruction, 16), 0x1F)
 end

-local function destination(instruction)
+local function destination(instruction: int) -> int
     return band(rshift(instruction, 11), 0x1F)
 end

-local function shift_amount(instruction)
+local function shift_amount(instruction: int) -> int
     return band(rshift(instruction, 6), 0x1F)
 end

-local function function_field(instruction)
+local function function_field(instruction: int) -> int
     return band(rshift(instruction, 0), 0x3F)
 end

 -- Placeholder for monkey-patched function.
-function instance:write_back_registers()
+function instance:write_back_registers() -> string
     return ""
 end

-function instance:decode_instruction(instruction)
+function instance:decode_instruction(instruction: number) -> bool, string, string?, bool
     if instruction == 0 then
         return true, "", nil, false
     end
@@ -69,11 +75,11 @@
     return handler(self, opcode, first_source, second_source, destination, shift_amount, function_field)
 end

-function instance:decode(read32)
+function instance:decode(read32: function(int) -> int) -> string
     local keep_decoding = true
     local branch_delay = false
     local next_address = ""
-    local ops = {}
+    local ops = {} : [string]

     while keep_decoding do
         local instruction = read32(self.program_counter)
@@ -120,13 +126,13 @@

 local DecodeInstance = {__index = instance}

-function mips_decode.new(decode_table, program_counter)
+function mips_decode.new(decode_table: {decode_handler}, program_counter: uint) -> table
     local instance = {
         decode_table = decode_table,
-        gpr_declared = {},
-        gpr_needs_writeback = {},
-        cp0r_declared = {},
-        cp0r_needs_writeback = {},
+        gpr_declared = {} : [bool],
+        gpr_needs_writeback = {} : [bool],
+        cp0r_declared = {} : [bool],
+        cp0r_needs_writeback = {} : [bool],
         program_counter = program_counter
     }

@@ -175,7 +181,7 @@
     "ra"
 }

-function mips_decode.register_name(register)
+function mips_decode.register_name(register: number) -> string
     return names[register + 1]
 end