scoundrel-ports/gb/ezgb.h

#ifndef EZGB_H
#define EZGB_H
/**
  EZgb: a set of helpers for easy GB indie development in pure C
  for Z88DK (in text mode)

  Created by Luxferre in 2026, released into public domain
*/

#include <gb/gb.h>
#include <conio.h>
#include <curses.h>

#define u8 unsigned char
#define u16 unsigned short
#define s8 signed char
#define s16 signed short

/* Generic constants */

#define SCREEN_WIDTH  20
#define SCREEN_HEIGHT 18
#define SCREEN_CENTER_X (SCREEN_WIDTH >> 1)
#define SCREEN_CENTER_Y (SCREEN_HEIGHT >> 1)
#define NL "\n"

#define EZJOY_UP 1
#define EZJOY_DN 2
#define EZJOY_LT 3
#define EZJOY_RT 4
#define EZJOY_A  5
#define EZJOY_B  6
#define EZJOY_SL 7
#define EZJOY_ST 8

/* RNG stuff */
static u16 _ez_entropy = 0;

u16 ezrand() {
  _ez_entropy = 1 + ((_ez_entropy >> 15) | (_ez_entropy << 1));
  return ((u16) rand()) ^ _ez_entropy;
}

u8 joy_input_wait() {
  u8 last_joy = 0, joy, pressed;
  /* wait until the previous key is released */
  while(joypad());
  /* wait for a new press */
  while(1) {
    ++_ez_entropy;
    joy = joypad();
    pressed = joy & ~last_joy;
    if(pressed & J_UP) return EZJOY_UP;
    if(pressed & J_DOWN) return EZJOY_DN;
    if(pressed & J_LEFT) return EZJOY_LT;
    if(pressed & J_RIGHT) return EZJOY_RT;
    if(pressed & J_A) return EZJOY_A;
    if(pressed & J_B) return EZJOY_B;
    if(pressed & J_SELECT) return EZJOY_SL;
    if(pressed & J_START) return EZJOY_ST;
    last_joy = joy;
    wait_vbl_done();
  }
}

/* wait until Start is pressed */
void wait_for_start() {
  u8 joy;
  while(1) {
    ++_ez_entropy;
    joy = joypad();
    if(joy & J_START) break;
    wait_vbl_done();
  }
}

/* randomize until Start is pressed */
void wait_for_start_rand() {
  u8 joy;
#ifdef _randomize
  _randomize();
#endif
  _ez_entropy = rand();
  while(1) {
    ++_ez_entropy;
    joy = joypad();
    if(joy & J_START) break;
    wait_vbl_done();
  }
  srand(_ez_entropy);
}

/* Sound methods */

void init_sound() {
  NR52_REG = 0x80;
  NR50_REG = 0x77;
  NR51_REG = 0xFF;
}

u16 get_timer_by_freq(u16 freq) {
  return (u16) (2048 - (131072 / freq));
}

void play_pulse(u8 channel, u16 freq, u16 duration) {
  u16 tm = get_timer_by_freq(freq);

  if(channel == 0) {
    NR10_REG = 0x00;
    NR11_REG = 0x80 | duration;
    NR12_REG = 0xF3;
    NR13_REG = tm & 255;
    NR14_REG = 0xC0 | (tm >> 8);
  } else {
    NR21_REG = 0x80 | duration;
    NR22_REG = 0xF3;
    NR23_REG = tm & 255;
    NR24_REG = 0xC0 | (tm >> 8);
  }
}

void play_jingle(u16 n1f1,
  u16 n1f2,
  u16 n2f1,
  u16 n2f2,
  u16 n3f1,
  u16 n3f2) {
  u16 i, dl = 2600;
  play_pulse(0, n1f1, 1);
  play_pulse(1, n1f2, 1);
  for(i=0;i<dl;++i);
  play_pulse(0, n2f1, 1);
  play_pulse(1, n2f2, 1);
  for(i=0;i<dl;++i);
  play_pulse(0, n3f1, 1);
  play_pulse(1, n3f2, 1);
}

/* Generic helper methods */

/* Array shuffle method */
void shuffle(s8 *array, u16 n) {
  u16 i, j, t;
  if(n > 1) {
    for(i=n-1;i>0;--i) {
      j = (u16) (ezrand()%(i+1));
      t = array[j];
      array[j] = array[i];
      array[i] = t;
    }
  }
}

/* Delay by n cycles */
void delay_cycles(u16 n) {
  u16 i;
  for(i=0;i<n;++i);
}

/* CC65 compat */

#define EZ_HLINE (char) 0x0e
#define EZ_VLINE (char) 0x0f
#define EZ_CORNER_UL (char) 0x1c
#define EZ_CORNER_UR (char) 0x1d
#define EZ_CORNER_DL (char) 0x1e
#define EZ_CORNER_DR (char) 0x1f

#define cprintf printf

void convdigits(char *s, u16 len) {
  u16 i;
  for(i=0;i<len;i++) {
    if(s[i] >= 0x30 && s[i] < 0x3A)
      s[i] -= 0x20;
  }
}

void cputcxy(u8 x, u8 y, char c) {
  gotoxy(x, y);
  cputc(c);
}

void cputsxy(u8 x, u8 y, char *s) {
  gotoxy(x, y);
  cprintf("%s", s);
}

void chlinexy(u8 x, u8 y, u8 l) {
  u8 i;
  gotoxy(x, y);
  for(i=0;i<l;++i) cputc(EZ_HLINE);
}

void cvlinexy(u8 x, u8 y, u8 l) {
  u8 i;
  for(i=0;i<l;++i) {
    gotoxy(x, y+i);
    cputc(EZ_VLINE);
  }
}

/* Draw a proper rectangle with corners */
void rect(u8 x, u8 y, u8 w, u8 h) {
  u8 i, bl_y = y + h - 1, tr_x = x + w - 1;
  gotoxy(x, y);
  cputc(EZ_CORNER_UL);
  for(i=0;i<w-2;++i) cputc(EZ_HLINE);
  cputc(EZ_CORNER_UR);
  for(i=0;i<h-2;++i) {
    gotoxy(x, y+i+1); cputc(EZ_VLINE);
    gotoxy(tr_x, y+i+1); cputc(EZ_VLINE);
  }
  gotoxy(x, bl_y);
  cputc(EZ_CORNER_DL);
  for(i=0;i<w-2;++i) cputc(EZ_HLINE);
  cputc(EZ_CORNER_DR);
}

void termreset() {
  clrscr();
  move_bkg(0, 0);
  gotoxy(0, 0);
}

void gamereset() {
  #asm
  jp 0
  #endasm
}

#endif