// SPDX-License-Identifier: GPL-2.0-or-later
//
// Boot-layout keyboard reports to keys, for GMMOS's USB and I2C keyboards.
//
// usb_hid.c's keyboard path with the console, /dev/input, the lock and key
// repeat taken out: what is left is edge detection and a table. US layout, as
// the live USB path is.

#include "core/types.h"
#include "core/defs.h"
#include "dev/kbd.h"
#include "gmmos/gmmos.h"

#define MOD_CTRL  0x11
#define MOD_SHIFT 0x22

static const uchar plain[0x39] = {
  0, 0, 0, 0,
  'a','b','c','d','e','f','g','h','i','j','k','l','m',
  'n','o','p','q','r','s','t','u','v','w','x','y','z',
  '1','2','3','4','5','6','7','8','9','0',
  '\n', 0x1B, '\b', '\t', ' ',
  '-','=','[',']','\\','#',';','\'','`',',','.','/',
};

static const uchar shifted[0x39] = {
  0, 0, 0, 0,
  'A','B','C','D','E','F','G','H','I','J','K','L','M',
  'N','O','P','Q','R','S','T','U','V','W','X','Y','Z',
  '!','@','#','$','%','^','&','*','(',')',
  '\n', 0x1B, '\b', '\t', ' ',
  '_','+','{','}','|','~',':','"','~','<','>','?',
};

static int
special(uchar u)
{
  switch (u) {
  case 0x4A: return KBD_HOME;
  case 0x4B: return KBD_PGUP;
  case 0x4C: return KBD_DEL;
  case 0x4D: return KBD_END;
  case 0x4E: return KBD_PGDN;
  case 0x4F: return KBD_RT;
  case 0x50: return KBD_LF;
  case 0x51: return KBD_DN;
  case 0x52: return KBD_UP;
  case 0x56: return '-';          // keypad minus and plus: the QR size keys
  case 0x57: return '+';
  case 0x58: return '\n';         // keypad Enter
  }
  return 0;
}

static int
was_down(const uchar *rep, uchar u)
{
  for (int i = 2; i < 8; i++)
    if (rep[i] == u)
      return 1;
  return 0;
}

void
gmmos_hid_report(struct gmmos_hidkeys *k, const uchar *boot)
{
  uchar mods = boot[0];

  for (int i = 2; i < 8; i++) {
    uchar u = boot[i];
    int c;

    if (u < 4 || was_down(k->prev, u))
      continue;
    if (u < 0x39)
      c = (mods & MOD_SHIFT) ? shifted[u] : plain[u];
    else
      c = special(u);
    if (c == 0)
      continue;
    if ((mods & MOD_CTRL) && c < KBD_SPECIAL) {
      if (c >= 'a' && c <= 'z')      c = c - 'a' + 1;
      else if (c >= 'A' && c <= 'Z') c = c - 'A' + 1;
      else continue;
    }
    if (k->qt - k->qh < (int)NELEM(k->q))
      k->q[k->qt++ % NELEM(k->q)] = c;
  }
  memmove(k->prev, boot, 8);
}

int
gmmos_hid_next(struct gmmos_hidkeys *k)
{
  if (k->qh == k->qt)
    return 0;
  return k->q[k->qh++ % NELEM(k->q)];
}