riverdelta/std.nil

function printlnI32(x: I32) = (
    printI32(x);
    print("\n");
);

function printlnInt(x: Int) = (
  printInt(x);
  print("\n");
);

function printI32(x: I32) = printInt(i32ToInt(x));

function printInt(x: Int) = (
  let mag = log10(x);

  loop (
    if mag == 0 then break;
    let base = pow(10, mag);

    let digit = x / base;
    print(stringForDigit(digit));

    x = x % base;
    mag = mag - 1;
  );

  print(stringForDigit(x % 10));
);

function stringForDigit(x: Int): String = 
  if x == 0 then "0"
  else if x == 1 then "1"
  else if x == 2 then "2"
  else if x == 3 then "3"
  else if x == 4 then "4"
  else if x == 5 then "5"
  else if x == 6 then "6"
  else if x == 7 then "7"
  else if x == 8 then "8"
  else if x == 9 then "9"
  else trap();

function log10(x: Int): Int = (
  let i = 0;
  loop (
    if x < 10 then break;
    i = i + 1;
    x = x / 10;
  );
  i
);

function pow(base: Int, exp: Int): Int = (
  let acc = 1;
  loop (
    if exp == 0 then break;
    acc = acc * base;
    exp = exp - 1;
  );
  acc
);

function println(s: String) = (
  print(s);
  print("\n");
);

mod rt (
    // Start the heap at 1024. In practice this could probably be as low as we want.
    global BASE_PTR: I32 = 1024_I32;
    global HEAD_PTR: I32 = 1024_I32;

    /*
    Every struct has a header of an I32 as a refcount.
    */

    // Allocate a new item. We do not deallocate anything yet.
    // lol.
    function allocateItem(objSize: I32, align: I32): I32 = (
        if align < 4_I32 then std.abort("invalid alignment");

        // Include the refcount header.
        let actualSize = 4_I32 + objSize;

        // Let's see whether we can fit the refcount into the align bits.
        // I happen to know that everything will always be at least 4 bytes aligned.
        let alignedPtr = std.alignUp(HEAD_PTR, align);
        let actualObjPtr = if (alignedPtr - HEAD_PTR) > align then (
            alignedPtr - 4_I32
        ) else (
            // Take up the next spot.
            alignedPtr + align - 4_I32
        );

        let newHeadPtr = actualObjPtr + actualSize;

        if newHeadPtr > __memory_size() then (
            // 16 pages, very arbitrary.
            let result = __memory_grow(16_I32);
            // If allocation failed we get -1. We don't have negative numbers yet, lol.
            if result > 100000000_I32 then (
                std.abort("failed to grow memory");
            );
        );

        0_I32
    );
);

function alignUp(x: I32, align: I32): I32 = (x + (align - 1_I32)) & !(align - 1_I32);

function i32ToInt(x: I32): Int = __i32_extend_to_i64_u(x);

function abort(message: String) = (
    print("fatal error: ");
    print(message);
    println(".. aborting");
    trap();
);

function main() = (
    std.rt.allocateItem(100000000_I32, 8_I32);
);