er_pageturn.h

Go to the documentation of this file.

 
#pragma once
 
#include <stdint.h>

typedef enum : int8_t {
  k_er_dir_prev = -1, 
  k_er_dir_none = 0,  
  k_er_dir_next = 1,  
} er_dir_t;

typedef enum : uint32_t {
  k_er_pt_thirds = 3U,          
  k_er_page_last = 0xFFFFFFFFU, 
} er_pageturn_const_t;

static inline er_dir_t er_tap_to_dir(int32_t x, int32_t width)
{
  if (width <= 0) {
    return k_er_dir_none;
  }
  const int32_t third = width / (int32_t)k_er_pt_thirds;
  if (x >= (width - third)) {
    return k_er_dir_next;
  }
  if (x < third) {
    return k_er_dir_prev;
  }
  return k_er_dir_none;
}

static inline er_dir_t er_buttons_to_dir(bool sw1_pressed, bool sw2_pressed)
{
  if (sw1_pressed) {
    return k_er_dir_prev;
  }
  if (sw2_pressed) {
    return k_er_dir_next;
  }
  return k_er_dir_none;
}

static inline bool er_pageturn_step(uint32_t  chapter,
                                    uint32_t  page,
                                    uint32_t  pages,
                                    uint32_t  ch_count,
                                    er_dir_t  dir,
                                    uint32_t* out_chap,
                                    uint32_t* out_page,
                                    bool*     out_crossed)
{
  *out_chap    = chapter;
  *out_page    = page;
  *out_crossed = false;
  if (dir == k_er_dir_next) {
    if ((page + 1U) < pages) {
      *out_page = page + 1U;
      return true;
    }
    if ((chapter + 1U) < ch_count) {
      *out_chap    = chapter + 1U;
      *out_page    = 0U;
      *out_crossed = true;
      return true;
    }
    return false;
  }
  if (dir == k_er_dir_prev) {
    if (page > 0U) {
      *out_page = page - 1U;
      return true;
    }
    if (chapter > 0U) {
      *out_chap    = chapter - 1U;
      *out_page    = (uint32_t)k_er_page_last;
      *out_crossed = true;
      return true;
    }
    return false;
  }
  return false;
}