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//: Phase 3: Start running a loaded and transformed recipe.
//:
//: So far we've seen recipes as lists of instructions, and instructions point
//: at other recipes. To kick things off mu needs to know how to run certain
//: 'primitive' recipes. That will then give the ability to run recipes
//: containing these primitives.
//:
//: This layer defines a skeleton with just two primitive recipes: IDLE which
//: does nothing, and COPY, which can copy numbers from one memory location to
//: another. Later layers will add more primitives.

:(scenario copy_literal)
recipe main [
  1:integer <- copy 23:literal
]
+run: instruction main/0
+run: ingredient 0 is 23
+mem: storing 23 in location 1

:(scenario copy)
recipe main [
  1:integer <- copy 23:literal
  2:integer <- copy 1:integer
]
+run: instruction main/1
+run: ingredient 0 is 1
+mem: location 1 is 23
+mem: storing 23 in location 2

:(before "End Types")
// Book-keeping while running a recipe.
//: Later layers will change this.
struct routine {
  recipe_number running_recipe;
  size_t running_at;
  routine(recipe_number r) :running_recipe(r), running_at(0) {}
};

:(before "End Globals")
routine* Current_routine = NULL;

:(code)
void run(recipe_number r) {
  run(routine(r));
}

void run(routine rr)
{  // curly on a separate line, because later layers will modify signature
  Current_routine = &rr;
  while (!done(rr))  // later layers will modify condition
  {
    // Running One Instruction.
    vector<instruction>& instructions = steps(rr);
    size_t& pc = running_at(rr);
//?     trace("foo") << "2: " << pc << " " << &pc; //? 1
    if (instructions[pc].is_label) { ++pc; continue; }
//?     cout << "AAA " << Trace_stream << " ^" << Trace_stream->dump_layer << "$\n"; //? 1
//?     trace("foo") << "2.5: " << pc << " " << &pc; //? 1
    trace("run") << "instruction " << recipe_name(rr) << '/' << pc;
//?     cout << "operation " << instructions[pc].operation << '\n'; //? 3
//?     if (!instructions[pc].products.empty()) trace("foo") << "AAA product 0 is " << instructions[pc].products[0].to_string(); //? 1
    switch (instructions[pc].operation) {
      // Primitive Recipe Implementations
      case COPY: {
        trace("run") << "ingredient 0 is " << instructions[pc].ingredients[0].name;
        vector<int> data = read_memory(instructions[pc].ingredients[0]);
        write_memory(instructions[pc].products[0], data);
        break;
      }
      // End Primitive Recipe Implementations
      default: {
        cout << "not a primitive op: " << instructions[pc].operation << '\n';
      }
    }
//?     trace("foo") << "3: " << pc << " " << &pc; //? 1
    ++pc;
  }
  Current_routine = NULL;
}

//: Some helpers.
//: We'll need to override these later as we change the definition of routine.
//: Important that they return referrences into the routine.

inline size_t& running_at(routine& rr) {
  return rr.running_at;
}

inline string recipe_name(routine& rr) {
  return Recipe[rr.running_recipe].name;
}

inline vector<instruction>& steps(routine& rr) {
  return Recipe[rr.running_recipe].steps;
}

inline bool done(routine& rr) {
  return running_at(rr) >= steps(rr).size();
}

:(before "End Commandline Parsing")
if (argc > 1) {
  for (int i = 1; i < argc; ++i) {
    load_and_transform(argv[i]);
  }
}

:(before "End Main")
if (!Run_tests) {
  setup();
  Trace_stream = new trace_stream;
//?   Trace_stream->dump_layer = "all"; //? 2
  transform_all();
  recipe_number r = Recipe_number[string("main")];
//?   Trace_stream->dump_layer = "all"; //? 1
  if (r) run(r);
  dump_memory();
}

:(code)
void load_and_transform(string filename) {
  ifstream fin(filename.c_str());
  if (!fin) {
    raise << "no such file " << filename << '\n';
    return;
  }
  fin >> std::noskipws;
  load(fin);
  transform_all();
  fin.close();
  // freeze everything so it doesn't get cleared by tests
  recently_added_recipes.clear();
  recently_added_types.clear();
}

//:: On startup, load everything in core.mu
:(before "End Load Recipes")
load_and_transform("core.mu");

:(code)
// helper for tests
void run(string form) {
  vector<recipe_number> tmp = load(form);
  transform_all();
  run(tmp.front());
}

//:: Reading from memory, writing to memory.

vector<int> read_memory(reagent x) {
//?   cout << "read_memory: " << x.to_string() << '\n'; //? 1
  vector<int> result;
  if (isa_literal(x)) {
    result.push_back(x.value);
    return result;
  }
  int base = x.value;
  size_t size = size_of(x);
  for (size_t offset = 0; offset < size; ++offset) {
    int val = Memory[base+offset];
    trace("mem") << "location " << base+offset << " is " << val;
    result.push_back(val);
  }
  return result;
}

void write_memory(reagent x, vector<int> data) {
  if (is_dummy(x)) return;
  int base = x.value;
  if (size_of(x) != data.size())
    raise << "size mismatch in storing to " << x.to_string() << '\n';
  for (size_t offset = 0; offset < data.size(); ++offset) {
    trace("mem") << "storing " << data[offset] << " in location " << base+offset;
    Memory[base+offset] = data[offset];
  }
}

:(code)
size_t size_of(const reagent& r) {
  return size_of(r.types);
}
size_t size_of(const vector<type_number>& types) {
  // End size_of(types) Cases
  return 1;
}

bool is_dummy(const reagent& x) {
  return x.name == "_";
}

bool isa_literal(const reagent& r) {
  return r.types.size() == 1 && r.types[0] == 0;
}

:(scenario run_label)
recipe main [
  +foo
  1:integer <- copy 23:literal
  2:integer <- copy 1:integer
]
+run: instruction main/1
+run: instruction main/2
-run: instruction main/0

:(scenario run_dummy)
recipe main [
  _ <- copy 0:literal
]
+run: instruction main/0
>
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//: You guessed right: the '000' prefix means you should start reading here.
//:
//: This project is set up to load all files with a numeric prefix. Just
//: create a new file and start hacking.
//:
//: The first few files (00*) are independent of what this program does, an
//: experimental skeleton that will hopefully make it both easier for others to
//: understand and more malleable, easier to rewrite and remould into radically
//: different shapes without breaking in subtle corner cases. The premise is
//: that understandability and rewrite-friendliness are related in a virtuous
//: cycle. Doing one well makes it easier to do the other.
//:
//: Lower down, this file contains a legal, bare-bones C++ program. It doesn't
//: do anything yet; subsequent files will contain :(...) directives to insert
//: lines into it. For example:
//:   :(after "more events")
//: This directive means: insert the following lines after a line in the
//: program containing the words "more events".
//:
//: A simple tool is included to 'tangle' all the files together in sequence
//: according to their directives into a single source file containing all the
//: code for the project, and then feed the source file to the compiler.
//: (It'll drop these comments starting with a '//:' prefix that only make
//: sense before tangling.)
//:
//: Directives free up the programmer to order code for others to read rather
//: than as forced by the computer or compiler. Each individual feature can be
//: organized in a self-contained 'layer' that adds code to many different data
//: structures and functions all over the program. The right decomposition into
//: layers will let each layer make sense in isolation.
//:
//:   "If I look at any small part of it, I can see what is going on -- I don't
//:   need to refer to other parts to understand what something is doing.
//:
//:   If I look at any large part in overview, I can see what is going on -- I
//:   don't need to know all the details to get it.
//:
//:   Every level of detail is as locally coherent and as well thought-out as
//:   any other level."
//:
//:       -- Richard Gabriel, "The Quality Without A Name"
//:          (http://dreamsongs.com/Files/PatternsOfSoftware.pdf, page 42)
//:
//: Directives are powerful; they permit inserting or modifying any point in
//: the program. Using them tastefully requires mapping out specific lines as
//: waypoints for future layers to hook into. Often such waypoints will be in
//: comments, capitalized to hint that other layers rely on their presence.
//:
//: A single waypoint might have many different code fragments hooking into
//: it from all over the codebase. Use 'before' directives to insert
//: code at a location in order, top to bottom, and 'after' directives to
//: insert code in reverse order. By convention waypoints intended for insertion
//: before begin with 'End'. Notice below how the layers line up above the "End
//: Foo" waypoint.
//:
//:   File 001          File 002                File 003
//:   ============      ===================     ===================
//:   // Foo
//:   ------------
//:              <----  :(before "End Foo")
//:                     ....
//:                     ...
//:   ------------
//:              <----------------------------  :(before "End Foo")
//:                                             ....
//:                                             ...
//:   // End Foo
//:   ============
//:
//: Here's part of a layer in color: http://i.imgur.com/0eONnyX.png. Directives
//: are shaded dark.
//:
//: Layers do more than just shuffle code around. In a well-organized codebase
//: it should be possible to stop loading after any file/layer, build and run
//: the program, and pass all tests for loaded features. (Relevant is
//: http://youtube.com/watch?v=c8N72t7aScY, a scene from "2001: A Space
//: Odyssey".) Get into the habit of running the included script called
//: 'test_layers' before you commit any changes.
//:
//: This 'subsetting guarantee' ensures that this directory contains a
//: cleaned-up narrative of the evolution of this codebase. Organizing
//: autobiographically allows newcomers to rapidly orient themselves, reading
//: the first few files to understand a simple gestalt of a program's core
//: purpose and features, and later gradually working their way through other
//: features as the need arises.
//:
//: Programmers shouldn't need to understand everything about a program to
//: hack on it. But they shouldn't be prevented from a thorough understanding
//: of each aspect either. The goal of layers is to reward curiosity.

// Includes
// End Includes

// Types
// End Types

// Function prototypes are auto-generated in the 'build' script; define your
// functions in any order. Just be sure to declare each function header all on
// one line, ending with the '{'. Our auto-generation scripts are too minimal
// and simple-minded to handle anything else.
#include "function_list"  // by convention, files ending with '_list' are auto-generated

// Globals
//
// All statements in this section should always define a single variable on a
// single line. The 'build' script will simple-mindedly auto-generate extern
// declarations for them. Remember to define (not just declare) constants with
// extern linkage in this section, since C++ global constants have internal
// linkage by default.
//
// End Globals

int main(int argc, char* argv[]) {
  atexit(reset);
  // we require a 32-bit little-endian system
  assert(sizeof(int) == 4);
  assert(sizeof(float) == 4);
  assert_little_endian();

  // End One-time Setup

  // Commandline Parsing
  // End Commandline Parsing

  // End Main

  return 0;
}

// Unit Tests
// End Unit Tests

//: our first directive; insert the following headers at the start of the program
:(before "End Includes")
#include <assert.h>
#include <stdlib.h>

//: Without directives or with the :(code) directive, lines get added at the
//: end.
//:
//: Regardless of where functions are defined, we can call them anywhere we
//: like as long as we format the function header in a specific way: put it
//: all on a single line without indent, end the line with ') {' and no
//: trailing whitespace. As long as functions uniformly start this way, our
//: 'build' script contains a little command to automatically generate
//: declarations for them.
:(code)
void reset() {
  // End Reset
}

void assert_little_endian() {
  const int x = 1;
  const char* y = reinterpret_cast<const char*>(&x);
  if (*y != 1) {
    cerr << "SubX requires a little-endian processor. Do you have Intel (or AMD or Atom) inside?\n";
    exit(1);
  }
}
:(before "End Includes")
#include<iostream>
using std::cerr;