tdkpin/original/TDKPIN_MECHANICS_RESTORED.c

/*
 * HISTORICAL PARTIAL mechanics transcription for TDKPIN.EXE.
 *
 * Target SHA-256:
 *   a9022f1894e3e6e21fc42e8f6c932f7c549ca77f63aaa0c488bb9d55d9d0174c
 *
 * This superseded intermediate is retained only as provenance for the earlier
 * live-probe work. It is not part of the completed readable-C deliverable.
 * The authoritative complete address-linked implementations are under
 * reconstructed/, especially tdkpin_flipper_collision.c,
 * tdkpin_flipper_bitmap_geometry.c, tdkpin_physics.c, and tdkpin_timer_tick.c.
 */

#include <stdbool.h>
#include <stdint.h>

enum {
    SOUND_RESOURCE_BASE = 2000,
    SOUND_CLAW_CAPTURE = SOUND_RESOURCE_BASE + 15,
    SOUND_CLAW_RELEASE = SOUND_RESOURCE_BASE + 16,
    SOUND_FLIPPER_MOVE = SOUND_RESOURCE_BASE + 21,
};

typedef struct {
    int16_t x;
    int16_t y;
    int16_t width;
    int16_t height;
} RectI16;

typedef struct {
    bool left_control_down;  /* object +0xbda; scan code 0x1d */
    bool keypad_enter_down;  /* object +0xbdb; scan code 0x1c */
    int16_t left_position;   /* object +0xbd4; recovered range 0..1 */
    int16_t right_position;  /* object +0xbd6; recovered range 0..1 */
} FlipperState;

typedef enum {
    CLAW_OPENING_OR_IDLE = 0,
    CLAW_CLOSING = 1,
} ClawSpriteBank;

typedef struct {
    bool active;             /* DAT_1028_07ca */
    uint16_t frame;          /* DAT_1028_086d; initialized to 10 */
    uint16_t target_frame;   /* DAT_1028_086f; initialized to 10 */
    ClawSpriteBank bank;     /* DAT_1028_0873 */
    bool animation_blocked;  /* DAT_1028_0874 */
    bool ball_suspended;     /* game object +0xbdf */
} ClawState;

typedef struct {
    uint16_t low;
    int16_t high;
} MillipixelWords;

typedef struct {
    MillipixelWords x;
    MillipixelWords y;
} RawClawReleasePosition;

typedef struct {
    float x;
    float y;
} Vec2F;

/*
 * FUN_1008_0002 at 1008:0002.
 * The called loader/player resolves argument N as Win16 WAVE resource 2000+N.
 */
static void play_sound_number(uint16_t number)
{
    if (sound_is_not_muted() && sound_device_is_available()) {
        play_wave_resource(SOUND_RESOURCE_BASE + number);
    }
}
/*
 * FUN_1000_638e / FUN_1000_6bf8 (keyboard release/press branches).
 * The original controls are binary input flags.  Motion happens later in
 * update_flippers(), once per changed edge.
 */
static void set_flipper_key(FlipperState *state, uint8_t scan_code, bool down)
{
    if (scan_code == 0x1d) {
        state->left_control_down = down;
    } else if (scan_code == 0x1c) {
        state->keypad_enter_down = down;
    }
}

/*
 * FUN_1000_7ed9 at 1000:7ed9 and FUN_1000_8b0d at 1000:8b0d.
 * delta is -1 for key-down and +1 for key-up.  The first routine updates
 * the live collision geometry and always starts sound 2021; the second moves
 * the matching rendered flipper geometry.
 */
static void move_flipper(int flipper_number, int delta)
{
    play_sound_number(21);
    update_flipper_collision_geometry(flipper_number, delta);
    update_flipper_bitmap_geometry(flipper_number, delta);
}

/* FUN_1000_99f0 at 1000:99f0. */
static void update_flippers(FlipperState *state)
{
    if (state->left_control_down && state->left_position == 0) {
        state->left_position++;
        move_flipper(1, -1);
    } else if (!state->left_control_down && state->left_position != 0) {
        state->left_position--;
        move_flipper(1, +1);
    }

    if (state->keypad_enter_down && state->right_position == 0) {
        state->right_position++;
        move_flipper(2, -1);
    } else if (!state->keypad_enter_down && state->right_position != 0) {
        state->right_position--;
        move_flipper(2, +1);
    }
}

/*
 * FUN_1008_0e08 at 1008:0e08.
 * Resource 900 is a 900x296 sheet: nine 100x74 frames in each of four rows.
 * Closing uses rows 0/74; opening and returning use rows 148/222.  The
 * destination is the logical playfield rectangle x=238, y=47, w=100, h=74.
 */
static RectI16 claw_source_rect(uint16_t frame, ClawSpriteBank bank)
{
    uint16_t column_frame = frame;
    int16_t source_y = bank == CLAW_CLOSING ? 0 : 148;

    if (column_frame > 9) {
        source_y += 74;
        column_frame -= 9;
    }

    return (RectI16){
        .x = (int16_t)((column_frame - 1) * 100),
        .y = source_y,
        .width = 100,
        .height = 74,
    };
}

static void render_claw(uint16_t frame, ClawSpriteBank bank)
{
    const RectI16 destination = {238, 47, 100, 74};

    if (frame == 0) {
        restore_playfield_background(destination);
    } else {
        blit_claw_sprite(claw_source_rect(frame, bank), destination);
    }
}

/* The only terminal frames selected by the collision branch at 1000:c79c. */
static const uint16_t CLAW_TERMINAL_FRAMES[4] = {1, 6, 7, 18};

/*
 * Raw signed 32-bit millipixel positions assigned by export ordinal 10 at
 * 1000:eab1. FUN_1000_9bca adds 500, divides by 1000, then subtracts the
 * eight-pixel ball radius only for bitmap placement. The physics position is
 * therefore the raw value divided by 1000, not a 16.16 fixed-point number.
 */
static RawClawReleasePosition raw_claw_release_position(uint16_t frame)
{
    switch (frame) {
    case 1:
    case 3:
        return (RawClawReleasePosition){{0xefd0, 3}, {0x30b0, 1}};
    case 2:
        return (RawClawReleasePosition){{0xf3b8, 3}, {0x3c68, 1}};
    case 4:
        return (RawClawReleasePosition){{0xfb88, 3}, {0x4ff0, 1}};
    case 5:
        return (RawClawReleasePosition){{0x0f10, 4}, {0x5f90, 1}};
    case 6:
        return (RawClawReleasePosition){{0x1eb0, 4}, {0x6f30, 1}};
    case 7:
        return (RawClawReleasePosition){{0x3238, 4}, {0x7ae8, 1}};
    case 8:
        return (RawClawReleasePosition){{0x3df0, 4}, {0x7ed0, 1}};
    case 9:
        return (RawClawReleasePosition){{0x4d90, 4}, {0x8a88, 1}};
    case 18:
        return (RawClawReleasePosition){{0xf588, 4}, {0x6760, 1}};
    default:
        unreachable_original_state();
        return (RawClawReleasePosition){{0, 0}, {0, 0}};
    }
}

static int32_t join_millipixel_words(MillipixelWords value)
{
    return ((int32_t)value.high << 16) | value.low;
}

static Vec2F claw_release_position_pixels(uint16_t frame)
{
    RawClawReleasePosition raw = raw_claw_release_position(frame);
    return (Vec2F){
        join_millipixel_words(raw.x) / 1000.0f,
        join_millipixel_words(raw.y) / 1000.0f,
    };
}

/*
 * Real48 constants loaded in 1000:eab1 after converting speed scalar 3800.
 * The result is millipixels per timer tick. Only 1, 6, 7, and 18 are selected
 * as random terminal frames, but all switch cases are retained here.
 */
static Vec2F claw_release_velocity_millipixels_per_tick(uint16_t frame)
{
    switch (frame) {
    case 1:  return (Vec2F){3800.0f * -0.60f, 3800.0f * 0.00f};
    case 2:  return (Vec2F){3800.0f * -0.45f, 3800.0f * 0.05f};
    case 3:  return (Vec2F){3800.0f * -0.70f, 3800.0f * 0.30f};
    case 4:  return (Vec2F){3800.0f * -0.30f, 3800.0f * 0.20f};
    case 5:  return (Vec2F){3800.0f * -0.32f, 3800.0f * 0.22f};
    case 6:  return (Vec2F){3800.0f * -0.40f, 3800.0f * 0.60f};
    case 7:  return (Vec2F){3800.0f * -0.31f, 3800.0f * 0.70f};
    case 8:  return (Vec2F){3800.0f * -0.20f, 3800.0f * 0.80f};
    case 9:  return (Vec2F){3800.0f * -0.10f, 3800.0f * 0.90f};
    case 18: return (Vec2F){0.0f, 1000.0f};
    default:
        unreachable_original_state();
        return (Vec2F){0.0f, 0.0f};
    }
}

/* Object-id 0x59 branch inside FUN_1000_c79c at 1000:c79c. */
static void begin_claw_capture(ClawState *claw, uint16_t random_0_to_3)
{
    if (claw->animation_blocked) {
        return;
    }

    claw->active = true;
    claw->target_frame = CLAW_TERMINAL_FRAMES[random_0_to_3];
    claw->bank = CLAW_CLOSING;
    claw->ball_suspended = true;
    zero_ball_motion();

    /* These moving collision records are absent while the arm holds the ball. */
    set_collision_objects_enabled(12, 20, false);
    play_sound_number(15); /* recovered call immediately before this branch */
}

/* Claw branch of exported ordinal 10 at 1000:eab1. */
static void update_claw(ClawState *claw)
{
    if (!claw->active || claw->animation_blocked) {
        return;
    }

    if (claw->frame != claw->target_frame) {
        claw->frame += claw->frame < claw->target_frame ? 1 : -1;
        render_claw(claw->frame, claw->bank);
        return;
    }

    if (claw->frame == 10) {
        render_claw(0, CLAW_OPENING_OR_IDLE);
        if (claw->bank == CLAW_OPENING_OR_IDLE) {
            claw->active = false;
            set_collision_objects_enabled(12, 20, true);
        }
        return;
    }

    /* Terminal closing frame: redraw from the opening bank, release, return. */
    render_claw(claw->frame, CLAW_OPENING_OR_IDLE);
    claw->target_frame = 10;
    claw->bank = CLAW_OPENING_OR_IDLE;
    reset_ball_forces();
    set_ball_position_pixels(claw_release_position_pixels(claw->frame));
    set_ball_velocity_millipixels_per_tick(
        claw_release_velocity_millipixels_per_tick(claw->frame));

    commit_ball_position();
    play_sound_number(16);
    claw->ball_suspended = false;
}