ludic/runtime/native/core.ludic

# ============================================================================
# runtime/native/core.ludic — the Ludic runtime, written in Ludic.
#
# This is what the native backend links instead of a C runtime. Everything a
# game touches through a builtin — the framebuffer, rectangles, text, the
# registers, the RNG, input, the frame dump — is implemented right here in
# Ludic and compiled to machine code by ludicc like any other Ludic source.
#
# Underneath it there is exactly one layer, and it is not C: the compiler
# intrinsics (mem_alloc, peek8/poke8, peek32/poke32, file_open/file_write,
# read_byte, …) lower to direct calls into the platform's C ABI — malloc,
# fwrite, getchar. That ABI is the operating system's interface, the same floor
# Rust and Swift stand on. No C source is compiled at any point in the build.
#
# A builtin `clear(c)` in a game resolves to `rt_clear(c)` here; that is the
# whole protocol. Swap this file and you have swapped the runtime.
#
# This file is a fragment: ludicc splices it into every native build. It is not
# a `game`/`module` block of its own.
# ============================================================================

# ---- state ----------------------------------------------------------------
var rt_fb:    ptr = null     # framebuffer, one i32 (0x00RRGGBB) per pixel
var rt_fbw:   int = 320
var rt_fbh:   int = 240
var rt_regs:  ptr = null     # the 64 general-purpose game registers
var rt_rng:   int = 305419896      # xorshift32 state
var rt_alive: int = 1              # platform still running?

# 5x7 glyphs for ASCII 32..90, 7 rows per glyph, each row a 5-bit mask stored
# biased by '0' so the whole font is one printable string literal.
fn rt_font() -> str {
  return "00000004444404000000000000000000000IJ4:FC000000000000000000000000000000E>O>E0044O4400000448000O000000004012448@@>ACEIA>4<4444>>A168@ON11>11N26:BO22O@N11A>>@@NAA>O124888>AA>AA>>AA?11>04004000000000024842000O0O000842480>A164040000000>AAOAAANAANAAN>A@@@A>LBAAABLO@@L@@OO@@L@@@>A@GAA>AAAOAAA>44444>7222BB<ABDHDBA@@@@@@OAKEEAAAAIEECAA>AAAAA>NAAN@@@>AAAEB=NAANDBA>A@>1A>O444444AAAAAA>AAAAA:4AAAEEKAAA:4:AAAA:4444O1248@O"
}

fn rt_init() -> void {
  rt_fb = mem_alloc(320 * 240 * 4)
  rt_regs = mem_alloc(64 * 4)
  mem_set(rt_regs, 0, 64 * 4)
  rt_map = mem_alloc(96 * 64)
  mem_set(rt_map, 32, 96 * 64)
  rt_statusbuf = mem_alloc(96)
  poke8(rt_statusbuf, 0, 0)
  rt_image_init()
  rt_tt_init()
  rt_ui_init()
  rt_clear(0)
  if is_windowed() {
    win_open(rt_fbw, rt_fbh, 3, game_title())
  }
}

fn rt_shutdown() -> void {
  if is_windowed() {
    win_close()
    return
  }
  rt_dump_ppm("out.ppm")
}

# ---- framebuffer ----------------------------------------------------------
fn rt_clear(c: int) -> void {
  let n = rt_fbw * rt_fbh
  for i in 0 .. n {
    poke32(rt_fb, i, c)
  }
}

fn rt_put_px(x: int, y: int, c: int) -> void {
  if x < 0 { return }
  if y < 0 { return }
  if x >= rt_fbw { return }
  if y >= rt_fbh { return }
  poke32(rt_fb, y * rt_fbw + x, c)
}

fn rt_fill_rect(x: int, y: int, w: int, h: int, c: int) -> void {
  let x0 = max(0, x)
  let y0 = max(0, y)
  let x1 = min(rt_fbw, x + w)
  let y1 = min(rt_fbh, y + h)
  var j = y0
  while j < y1 {
    let row = j * rt_fbw
    var i = x0
    while i < x1 {
      poke32(rt_fb, row + i, c)
      i = i + 1
    }
    j = j + 1
  }
}

fn rt_frame_rect(x: int, y: int, w: int, h: int, c: int) -> void {
  rt_fill_rect(x, y, w, 1, c)
  rt_fill_rect(x, y + h - 1, w, 1, c)
  rt_fill_rect(x, y, 1, h, c)
  rt_fill_rect(x + w - 1, y, 1, h, c)
}

# Windowed: hand the framebuffer to the platform layer, which blits it into
# the view. Headless: nothing to do until shutdown writes the last frame out.
fn rt_present() -> void {
  if is_windowed() {
    win_present(rt_fb, rt_fbw, rt_fbh)
  }
}

# ---- text -----------------------------------------------------------------
fn rt_glyph(x: int, y: int, ch: int, colour: int, sc: int) -> void {
  var c = ch
  if c >= 97 {
    if c <= 122 { c = c - 32 }
  }
  if c < 32 { return }
  if c > 90 { return }
  let base = (c - 32) * 7
  let font = rt_font()
  for row in 0 .. 7 {
    let bits = peek8(font, base + row) - 48
    var b = bits
    for cc in 0 .. 5 {
      let on = b / 16
      if on == 1 {
        rt_fill_rect(x + cc * sc, y + row * sc, sc, sc, colour)
      }
      b = (b - on * 16) * 2
    }
  }
}

fn rt_text(x: int, y: int, s: str, colour: int, sc: int) -> void {
  var i = 0
  var cx = x
  var ch = peek8(s, 0)
  while ch != 0 {
    rt_glyph(cx, y, ch, colour, sc)
    cx = cx + 6 * sc
    i = i + 1
    ch = peek8(s, i)
  }
}

fn rt_text_int(x: int, y: int, n: int, colour: int, sc: int) -> void {
  if n == 0 {
    rt_glyph(x, y, 48, colour, sc)
    return
  }
  var v = n
  var cx = x
  if v < 0 {
    rt_glyph(cx, y, 45, colour, sc)
    cx = cx + 6 * sc
    v = 0 - v
  }
  var digits = 0
  var t = v
  while t > 0 {
    digits = digits + 1
    t = t / 10
  }
  var p = digits
  while p > 0 {
    var div = 1
    for k in 1 .. p {
      div = div * 10
    }
    rt_glyph(cx, y, 48 + (v / div) % 10, colour, sc)
    cx = cx + 6 * sc
    p = p - 1
  }
}

# ---- registers ------------------------------------------------------------
fn rt_reg(i: int) -> int {
  if i < 0 { return 0 }
  if i >= 64 { return 0 }
  return peek32(rt_regs, i)
}

fn rt_set_reg(i: int, v: int) -> void {
  if i < 0 { return }
  if i >= 64 { return }
  poke32(rt_regs, i, v)
}

# ---- rng (xorshift32) -----------------------------------------------------
fn rt_seed(s: int) -> void {
  if s == 0 {
    rt_rng = 305419896
    return
  }
  rt_rng = s
}

# xorshift32 (Marsaglia). Runs on the raw 32-bit pattern, so the sign bit is
# masked off only when a caller asks for a number.
fn rt_next_rand() -> int {
  var x = rt_rng
  x = (x ^ (x << 13))
  x = (x ^ (x >> 17))
  x = (x ^ (x << 5))
  rt_rng = x
  return (x & 2147483647)
}

fn rt_rng_range(lo: int, hi: int) -> int {
  if hi <= lo { return lo }
  return lo + rt_next_rand() % (hi - lo + 1)
}

fn rt_rng_chance(pct: int) -> bool {
  return rt_next_rand() % 100 < pct
}

# ---- platform: input ------------------------------------------------------
fn rt_poll() -> int {
  if is_windowed() {
    return win_poll()
  }
  let c = read_byte()
  if c < 0 {
    rt_alive = 0
    return 0
  }
  if c == 113 {          # 'q' quits, as in the headless C platform
    rt_alive = 0
  }
  return c
}

fn rt_running() -> bool {
  if is_windowed() {
    return win_running()
  }
  return rt_alive
}

# ---- writing the frame out ------------------------------------------------
fn rt_put_str(buf: ptr, at: int, s: str) -> int {
  var i = 0
  var n = at
  var ch = peek8(s, 0)
  while ch != 0 {
    poke8(buf, n, ch)
    n = n + 1
    i = i + 1
    ch = peek8(s, i)
  }
  return n
}

fn rt_put_int(buf: ptr, at: int, v: int) -> int {
  if v == 0 {
    poke8(buf, at, 48)
    return at + 1
  }
  var digits = 0
  var t = v
  while t > 0 {
    digits = digits + 1
    t = t / 10
  }
  var n = at
  var p = digits
  while p > 0 {
    var div = 1
    for k in 1 .. p {
      div = div * 10
    }
    poke8(buf, n, 48 + (v / div) % 10)
    n = n + 1
    p = p - 1
  }
  return n
}

fn rt_dump_ppm(path: str) -> void {
  let f = file_open(path, "wb")
  if (f == null) { return }

  let hdr = mem_alloc(64)
  var n = rt_put_str(hdr, 0, "P6\n")
  n = rt_put_int(hdr, n, rt_fbw)
  n = rt_put_str(hdr, n, " ")
  n = rt_put_int(hdr, n, rt_fbh)
  n = rt_put_str(hdr, n, "\n255\n")
  file_write(f, hdr, n)

  let px = rt_fbw * rt_fbh
  let buf = mem_alloc(px * 3)
  for i in 0 .. px {
    let c = peek32(rt_fb, i)
    poke8(buf, i * 3, (c / 65536) % 256)
    poke8(buf, i * 3 + 1, (c / 256) % 256)
    poke8(buf, i * 3 + 2, c % 256)
  }
  file_write(f, buf, px * 3)
  file_close(f)
  mem_free(buf)
  mem_free(hdr)
}

import "inflate.ludic"
import "image.ludic"
import "truetype.ludic"
import "ui.ludic"

# ---- tilemap --------------------------------------------------------------
# A character grid the game paints with map_row() and reads with tile(). Stored
# as one byte per cell in a flat buffer; out-of-bounds reads answer '#' so a
# caller can treat the edge of the world as wall without special-casing it.
var rt_map:  ptr = null
var rt_mapw: int = 0
var rt_maph: int = 0

fn rt_map_size(w: int, h: int) -> void {
  rt_mapw = clamp(w, 0, 96)
  rt_maph = clamp(h, 0, 64)
  mem_set(rt_map, 32, 96 * 64)
}

fn rt_map_row(y: int, s: str) -> void {
  if y < 0 { return }
  if y >= 64 { return }
  var x = 0
  var ch = peek8(s, 0)
  while ch != 0 {
    if x >= 96 { return }
    poke8(rt_map, y * 96 + x, ch)
    x = x + 1
    ch = peek8(s, x)
  }
}

fn rt_tile(x: int, y: int) -> int {
  if x < 0 { return 35 }
  if y < 0 { return 35 }
  if x >= rt_mapw { return 35 }
  if y >= rt_maph { return 35 }
  return peek8(rt_map, y * 96 + x)
}

# ---- status line ----------------------------------------------------------
# One persistent string of feedback/dialogue, copied into runtime-owned memory
# so it survives whatever the caller does with the original.
var rt_statusbuf: ptr = null

fn rt_status(s: str) -> void {
  var i = 0
  var ch = peek8(s, 0)
  while ch != 0 {
    if i >= 95 { ch = 0 }
    if ch != 0 {
      poke8(rt_statusbuf, i, ch)
      i = i + 1
      ch = peek8(s, i)
    }
  }
  poke8(rt_statusbuf, i, 0)
}

fn rt_status_text() -> ptr {
  return rt_statusbuf
}

# ---- snapshot: the runtime serialises its own half ------------------------
# The compiler writes the ECS (entities, components, archetype kinds) because
# only it knows their shape. Everything below belongs to the runtime, so the
# runtime writes it — same order both ways.
fn rt_save_state(f: ptr) -> void {
  let w = mem_alloc(16)
  poke32(w, 0, rt_rng)
  poke32(w, 1, rt_mapw)
  poke32(w, 2, rt_maph)
  poke32(w, 3, rt_alive)
  file_write(f, w, 16)
  file_write(f, rt_regs, 64 * 4)
  file_write(f, rt_map, 96 * 64)
  file_write(f, rt_statusbuf, 96)
  mem_free(w)
}

fn rt_load_state(f: ptr) -> void {
  let w = mem_alloc(16)
  file_read(f, w, 16)
  rt_rng = peek32(w, 0)
  rt_mapw = peek32(w, 1)
  rt_maph = peek32(w, 2)
  file_read(f, rt_regs, 64 * 4)
  file_read(f, rt_map, 96 * 64)
  file_read(f, rt_statusbuf, 96)
  mem_free(w)
}