converter/ibmpc_usb/ibmpc_usb.c

   1 /*
   2 Copyright 2019,2020 Jun Wako <wakojun@gmail.com>
   3
   4 This program is free software: you can redistribute it and/or modify
   5 it under the terms of the GNU General Public License as published by
   6 the Free Software Foundation, either version 2 of the License, or
   7 (at your option) any later version.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18 #include <stdint.h>
  19 #include <stdbool.h>
  20 #include "print.h"
  21 #include "util.h"
  22 #include "debug.h"
  23 #include "ibmpc.h"
  24 #include "host.h"
  25 #include "led.h"
  26 #include "matrix.h"
  27 #include "timer.h"
  28 #include "action.h"
  29 #include "ibmpc_usb.h"
  30 #include "ibmpc.h"
  31
  32
  33 static void matrix_make(uint8_t code);
  34 static void matrix_break(uint8_t code);
  35
  36 static int8_t process_cs1(uint8_t code);
  37 static int8_t process_cs2(uint8_t code);
  38 static int8_t process_cs3(uint8_t code);
  39
  40
  41 static uint8_t matrix[MATRIX_ROWS];
  42 #define ROW(code)      ((code>>3)&0x0F)
  43 #define COL(code)      (code&0x07)
  44
  45 static int16_t read_wait(uint16_t wait_ms)
  46 {
  47     uint16_t start = timer_read();
  48     int16_t code;
  49     while ((code = ibmpc_host_recv()) == -1 && timer_elapsed(start) < wait_ms);
  50     return code;
  51 }
  52
  53 static uint16_t read_keyboard_id(void)
  54 {
  55     uint16_t id = 0;
  56     int16_t  code = 0;
  57
  58     // Disable
  59     //code = ibmpc_host_send(0xF5);
  60
  61     // Read ID
  62     code = ibmpc_host_send(0xF2);
  63     if (code == -1) { id = 0xFFFF; goto DONE; }     // XT or No keyboard
  64     if (code != 0xFA) { id = 0xFFFE; goto DONE; }   // Broken PS/2?
  65
  66     // ID takes 500ms max TechRef [8] 4-41
  67     code = read_wait(500);
  68     if (code == -1) { id = 0x0000; goto DONE; }     // AT
  69     id = (code & 0xFF)<<8;
  70
  71     // Mouse responds with one-byte 00, this returns 00FF [y] p.14
  72     code = read_wait(500);
  73     id |= code & 0xFF;
  74
  75 DONE:
  76     // Enable
  77     //code = ibmpc_host_send(0xF4);
  78
  79     return id;
  80 }
  81
  82 void hook_early_init(void)
  83 {
  84     ibmpc_host_init();
  85     ibmpc_host_enable();
  86 }
  87
  88 void matrix_init(void)
  89 {
  90     debug_enable = true;
  91
  92     // initialize matrix state: all keys off
  93     for (uint8_t i=0; i < MATRIX_ROWS; i++) matrix[i] = 0x00;
  94
  95     return;
  96 }
  97
  98 /*
  99  * keyboard recognition
 100  *
 101  * 1. Send F2 to get keyboard ID
 102  *      a. no ACK(FA): XT keyobard
 103  *      b. ACK but no ID: 84-key AT keyboard CodeSet2
 104  *      c. ID is AB 83: PS/2 keyboard CodeSet2
 105  *      d. ID is BF BF: Terminal keyboard CodeSet3
 106  *      e. error on recv: maybe broken PS/2
 107  */
 108 uint8_t current_protocol = 0;
 109 uint16_t keyboard_id = 0x0000;
 110 keyboard_kind_t keyboard_kind = NONE;
 111 uint8_t matrix_scan(void)
 112 {
 113     // scan code reading states
 114     static enum {
 115         INIT,
 116         XT_RESET,
 117         XT_RESET_WAIT,
 118         XT_RESET_DONE,
 119         WAIT_AA,
 120         WAIT_AABF,
 121         WAIT_AABFBF,
 122         READ_ID,
 123         SETUP,
 124         LOOP,
 125     } state = INIT;
 126     static uint16_t init_time;
 127
 128
 129     if (ibmpc_error) {
 130         xprintf("\nERR:%02X\n", ibmpc_error);
 131
 132         // when recv error, neither send error nor buffer full
 133         if (!(ibmpc_error & (IBMPC_ERR_SEND | IBMPC_ERR_FULL))) {
 134             // keyboard init again
 135             if (state == LOOP) {
 136                 xprintf("init\n");
 137                 state = INIT;
 138             }
 139         }
 140
 141         // clear or process error
 142         ibmpc_error = IBMPC_ERR_NONE;
 143     }
 144
 145     // check ISR state debug
 146     if (ibmpc_isr_debug) {
 147         xprintf("\nISR:%04X\n", ibmpc_isr_debug);
 148         ibmpc_isr_debug = 0;
 149     }
 150
 151     // check protocol AT/XT
 152     if (ibmpc_protocol != current_protocol) {
 153         xprintf("\nPROTO:%02X\n", ibmpc_protocol);
 154         current_protocol = ibmpc_protocol;
 155     }
 156
 157     switch (state) {
 158         case INIT:
 159             xprintf("I%u ", timer_read());
 160             keyboard_kind = NONE;
 161             keyboard_id = 0x0000;
 162
 163             matrix_clear();
 164             clear_keyboard();
 165
 166             state = XT_RESET;
 167             break;
 168         case XT_RESET:
 169             // Reset XT-initialize keyboard
 170             // XT: hard reset 500ms for IBM XT Type-1 keyboard and clones
 171             // XT: soft reset 20ms min(clock Lo)
 172             ibmpc_host_disable();   // soft reset: inihibit(clock Lo/Data Hi)
 173             IBMPC_RST_LO();         // hard reset: reset pin Lo
 174
 175             init_time = timer_read();
 176             state = XT_RESET_WAIT;
 177             break;
 178         case XT_RESET_WAIT:
 179             if (timer_elapsed(init_time) > 500) {
 180                 state = XT_RESET_DONE;
 181             }
 182             break;
 183         case XT_RESET_DONE:
 184             IBMPC_RST_HIZ();        // hard reset: reset pin HiZ
 185             ibmpc_host_isr_clear();
 186             ibmpc_host_enable();    // soft reset: idle(clock Hi/Data Hi)
 187
 188             xprintf("X%u ", timer_read());
 189             init_time = timer_read();
 190             state = WAIT_AA;
 191             break;
 192         case WAIT_AA:
 193             // 1) Read BAT code and ID on keybaord power-up
 194             // For example, XT/AT sends 'AA' and Terminal sends 'AA BF BF' after BAT
 195             // AT 84-key: POR and BAT can take 900-9900ms according to AT TechRef [8] 4-7
 196             // AT 101/102-key: POR and BAT can take 450-2500ms according to AT TechRef [8] 4-39
 197             // 2) Read key typed by user or anything after error on protocol or scan code
 198             // This can happen in case of keyboard hotswap, unstable hardware, signal integrity problem or bug
 199
 200             /* wait until keyboard sends any code without 10000ms timeout
 201             if (timer_elapsed(init_time) > 10000) {
 202                 state = READ_ID;
 203             }
 204             */
 205             if (ibmpc_host_recv() != -1) {  // wait for AA
 206                 xprintf("W%u ", timer_read());
 207                 init_time = timer_read();
 208                 state = WAIT_AABF;
 209             }
 210             break;
 211         case WAIT_AABF:
 212             // NOTE: we can omit to wait BF BF
 213             // ID takes 500ms max? TechRef [8] 4-41, though 1ms is enough for 122-key Terminal 6110345
 214             if (timer_elapsed(init_time) > 500) {
 215                 state = READ_ID;
 216             }
 217             if (ibmpc_host_recv() != -1) {  // wait for BF
 218                 xprintf("W%u ", timer_read());
 219                 init_time = timer_read();
 220                 state = WAIT_AABFBF;
 221             }
 222             break;
 223         case WAIT_AABFBF:
 224             if (timer_elapsed(init_time) > 500) {
 225                 state = READ_ID;
 226             }
 227             if (ibmpc_host_recv() != -1) {  // wait for BF
 228                 xprintf("W%u ", timer_read());
 229                 state = READ_ID;
 230             }
 231             break;
 232         case READ_ID:
 233             xprintf("R%u ", timer_read());
 234
 235             // SKIDATA-2-DE(and some other keyboards?) stores 'Code Set' setting in nonvlatile memory
 236             // and keeps it until receiving reset. Sending reset here may be useful to clear it, perhaps.
 237             // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#select-alternate-scan-codesf0
 238             //ibmpc_host_send(0xFF);  // reset command
 239             //read_wait(500);         // BAT takes 600-900ms(84-key) or 300-500ms(101/102-key) [8] 4-7, 4-39
 240
 241             keyboard_id = read_keyboard_id();
 242             if (ibmpc_error) {
 243                 xprintf("\nERR:%02X\n", ibmpc_error);
 244                 ibmpc_error = IBMPC_ERR_NONE;
 245             }
 246
 247             if (0x0000 == keyboard_id) {            // CodeSet2 AT(IBM PC AT 84-key)
 248                 keyboard_kind = PC_AT;
 249             } else if (0xFFFF == keyboard_id) {     // CodeSet1 XT
 250                 keyboard_kind = PC_XT;
 251             } else if (0xFFFE == keyboard_id) {     // CodeSet2 PS/2 fails to response?
 252                 keyboard_kind = PC_AT;
 253             } else if (0x00FF == keyboard_id) {     // Mouse is not supported
 254                 xprintf("Mouse: not supported\n");
 255                 keyboard_kind = NONE;
 256 #ifdef G80_2551_SUPPORT
 257             } else if (0xAB86 == keyboard_id ||
 258                        0xAB85 == keyboard_id) {     // For G80-2551 and other 122-key terminal
 259                 // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#ab86
 260                 // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#ab85
 261
 262                 if ((0xFA == ibmpc_host_send(0xF0)) &&
 263                     (0xFA == ibmpc_host_send(0x03))) {
 264                     // switch to code set 3
 265                     keyboard_kind = PC_TERMINAL;
 266                 } else {
 267                     keyboard_kind = PC_AT;
 268                 }
 269 #endif
 270             } else if (0xBFB0 == keyboard_id) {     // IBM RT Keyboard
 271                 // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#bfb0
 272                 // TODO: LED indicator fix
 273                 //keyboard_kind = PC_TERMINAL_IBM_RT;
 274                 keyboard_kind = PC_TERMINAL;
 275             } else if (0xAB00 == (keyboard_id & 0xFF00)) {  // CodeSet2 PS/2
 276                 keyboard_kind = PC_AT;
 277             } else if (0xBF00 == (keyboard_id & 0xFF00)) {  // CodeSet3 Terminal
 278                 keyboard_kind = PC_TERMINAL;
 279             } else {
 280                 keyboard_kind = PC_AT;
 281             }
 282
 283             xprintf("ID:%04X(%d)\n", keyboard_id, keyboard_kind);
 284
 285             state = SETUP;
 286             break;
 287         case SETUP:
 288             xprintf("S%u ", timer_read());
 289             switch (keyboard_kind) {
 290                 case PC_XT:
 291                     break;
 292                 case PC_AT:
 293                     led_set(host_keyboard_leds());
 294                     break;
 295                 case PC_TERMINAL:
 296                     // Set all keys to make/break type
 297                     ibmpc_host_send(0xF8);
 298                     // This should not be harmful
 299                     led_set(host_keyboard_leds());
 300                     break;
 301                 default:
 302                     break;
 303             }
 304             state = LOOP;
 305             xprintf("L%u ", timer_read());
 306         case LOOP:
 307             {
 308                 uint16_t code = ibmpc_host_recv();
 309                 if (code == -1) {
 310                     // no code
 311                     break;
 312                 }
 313
 314                 // Keyboard Error/Overrun([3]p.26) or Buffer full
 315                 // Scan Code Set 1: 0xFF
 316                 // Scan Code Set 2 and 3: 0x00
 317                 // Buffer full(IBMPC_ERR_FULL): 0xFF
 318                 if (code == 0x00 || code == 0xFF) {
 319                     xprintf("\n!OVERRUN![");
 320
 321                     // read and ignore data
 322                     do {
 323                         wait_ms(10);
 324                     } while ((code = ibmpc_host_recv()) != -1);
 325                     xprintf("]\n");
 326
 327                     // clear stuck keys
 328                     matrix_clear();
 329                     clear_keyboard();
 330                     break;
 331                 }
 332
 333                 switch (keyboard_kind) {
 334                     case PC_XT:
 335                         if (process_cs1(code) == -1) state = INIT;
 336                         break;
 337                     case PC_AT:
 338                         if (process_cs2(code) == -1) state = INIT;
 339                         break;
 340                     case PC_TERMINAL:
 341                         if (process_cs3(code) == -1) state = INIT;
 342                         break;
 343                     default:
 344                         break;
 345                 }
 346             }
 347             break;
 348         default:
 349             break;
 350     }
 351     return 1;
 352 }
 353
 354 inline
 355 bool matrix_is_on(uint8_t row, uint8_t col)
 356 {
 357     return (matrix[row] & (1<<col));
 358 }
 359
 360 inline
 361 uint8_t matrix_get_row(uint8_t row)
 362 {
 363     return matrix[row];
 364 }
 365
 366 uint8_t matrix_key_count(void)
 367 {
 368     uint8_t count = 0;
 369     for (uint8_t i = 0; i < MATRIX_ROWS; i++) {
 370         count += bitpop(matrix[i]);
 371     }
 372     return count;
 373 }
 374
 375
 376 inline
 377 static void matrix_make(uint8_t code)
 378 {
 379     if (!matrix_is_on(ROW(code), COL(code))) {
 380         matrix[ROW(code)] |= 1<<COL(code);
 381     }
 382 }
 383
 384 inline
 385 static void matrix_break(uint8_t code)
 386 {
 387     if (matrix_is_on(ROW(code), COL(code))) {
 388         matrix[ROW(code)] &= ~(1<<COL(code));
 389     }
 390 }
 391
 392 void matrix_clear(void)
 393 {
 394     for (uint8_t i=0; i < MATRIX_ROWS; i++) matrix[i] = 0x00;
 395 }
 396
 397 void led_set(uint8_t usb_led)
 398 {
 399     // Sending before keyboard recognition may be harmful for XT keyboard
 400     if (keyboard_kind == NONE) return;
 401
 402     // XT keyobard doesn't support any command and it is harmful perhaps
 403     // https://github.com/tmk/tmk_keyboard/issues/635#issuecomment-626993437
 404     if (keyboard_kind == PC_XT) return;
 405
 406     // It should be safe to send the command to keyboards with AT protocol
 407     // - IBM Terminal doesn't support the command and response with 0xFE but it is not harmful.
 408     // - Some other Terminals like G80-2551 supports the command.
 409     //   https://geekhack.org/index.php?topic=103648.msg2894921#msg2894921
 410
 411     // TODO: PC_TERMINAL_IBM_RT support
 412     uint8_t ibmpc_led = 0;
 413     if (usb_led &  (1<<USB_LED_SCROLL_LOCK))
 414         ibmpc_led |= (1<<IBMPC_LED_SCROLL_LOCK);
 415     if (usb_led &  (1<<USB_LED_NUM_LOCK))
 416         ibmpc_led |= (1<<IBMPC_LED_NUM_LOCK);
 417     if (usb_led &  (1<<USB_LED_CAPS_LOCK))
 418         ibmpc_led |= (1<<IBMPC_LED_CAPS_LOCK);
 419     ibmpc_host_set_led(ibmpc_led);
 420 }
 421
 422
 423 /*******************************************************************************
 424  * XT: Scan Code Set 1
 425  *
 426  * See [3], [a]
 427  *
 428  * E0-escaped scan codes are translated into unused range of the matrix.(54-7F)
 429  *
 430  *     01-53: Normal codes used in original XT keyboard
 431  *     54-7F: Not used in original XT keyboard
 432  *
 433  *         0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
 434  *     50  -   -   -   -   *   *   x   x   x   x   *   *   *   *   *   *
 435  *     60  *   *   *   *   x   x   x   x   x   x   x   x   x   x   x   *
 436  *     70  x   *   *   x   *   *   x   *   *   x   *   x   *   x   x   *
 437  *
 438  * -: codes existed in original XT keyboard
 439  * *: E0-escaped codes translated
 440  * x: Non-espcaped codes(Some are not used in real keyboards probably)
 441  *
 442  * Codes assigned in range 54-7F:
 443  *
 444  *     50  -                60  Up*                 70  KANAx
 445  *     51  -                61  Left*               71  Insert*
 446  *     52  -                62  Down*               72  Delete*
 447  *     53  -                63  Right*              73  ROx
 448  *     54  PrintScr*        64  F13x                74  Home*
 449  *     55  Pause*           65  F14x                75  End*
 450  *     56  Euro2x           66  F15x                76  F24x
 451  *     57  F11x             67  F16x                77  PageUp*
 452  *     58  F12x             68  F17x                78  PageDown*
 453  *     59  Keypad=x         69  F18x                79  HENKANx
 454  *     5A  LGUI*            6A  F19x                7A  RCTL*
 455  *     5B  RGUI*            6B  F20x                7B  MUHENKANx
 456  *     5C  APP*             6C  F21x                7C  RALT*
 457  *     5D  Mute*            6D  F22x                7D  JPYx
 458  *     5E  Volume Down*     6E  F23x                7E  Keypad,x
 459  *     5F  Volume Up*       6F  Keypad Enter*       7F  Keypad/ *
 460  */
 461 static uint8_t cs1_e0code(uint8_t code) {
 462     switch(code) {
 463         // Original IBM XT keyboard doesn't use E0-codes probably
 464         // Some XT compatilble keyobards need these keys?
 465         case 0x37: return 0x54; // Print Screen
 466         case 0x46: return 0x55; // Ctrl + Pause
 467         case 0x5B: return 0x5A; // Left  GUI
 468         case 0x5C: return 0x5B; // Right GUI
 469         case 0x5D: return 0x5C; // Application
 470         case 0x20: return 0x5D; // Mute
 471         case 0x2E: return 0x5E; // Volume Down
 472         case 0x30: return 0x5F; // Volume Up
 473         case 0x48: return 0x60; // Up
 474         case 0x4B: return 0x61; // Left
 475         case 0x50: return 0x62; // Down
 476         case 0x4D: return 0x63; // Right
 477         case 0x1C: return 0x6F; // Keypad Enter
 478         case 0x52: return 0x71; // Insert
 479         case 0x53: return 0x72; // Delete
 480         case 0x47: return 0x74; // Home
 481         case 0x4F: return 0x75; // End
 482         case 0x49: return 0x77; // Page Up
 483         case 0x51: return 0x78; // Page Down
 484         case 0x1D: return 0x7A; // Right Ctrl
 485         case 0x38: return 0x7C; // Right Alt
 486         case 0x35: return 0x7F; // Keypad /
 487
 488         // Shared matrix cell with other keys
 489         case 0x5E: return 0x70; // Power (KANA)
 490         case 0x5F: return 0x79; // Sleep (HENKAN)
 491         case 0x63: return 0x7B; // Wake  (MUHENKAN)
 492
 493         default:
 494            xprintf("!CS1_E0_%02X!\n", code);
 495            return code;
 496     }
 497     return 0x00;
 498 }
 499
 500 static int8_t process_cs1(uint8_t code)
 501 {
 502     static enum {
 503         INIT,
 504         E0,
 505         // Pause: E1 1D 45, E1 9D C5 [a] (TODO: test)
 506         E1,
 507         E1_1D,
 508         E1_9D,
 509     } state = INIT;
 510
 511     switch (state) {
 512         case INIT:
 513             switch (code) {
 514                 case 0xE0:
 515                     state = E0;
 516                     break;
 517                 case 0xE1:
 518                     state = E1;
 519                     break;
 520                 default:
 521                     if (code < 0x80)
 522                         matrix_make(code);
 523                     else
 524                         matrix_break(code & 0x7F);
 525                     break;
 526             }
 527             break;
 528         case E0:
 529             switch (code) {
 530                 case 0x2A:
 531                 case 0xAA:
 532                 case 0x36:
 533                 case 0xB6:
 534                     //ignore fake shift
 535                     state = INIT;
 536                     break;
 537                 default:
 538                     if (code < 0x80)
 539                         matrix_make(cs1_e0code(code));
 540                     else
 541                         matrix_break(cs1_e0code(code & 0x7F));
 542                     state = INIT;
 543                     break;
 544             }
 545             break;
 546         case E1:
 547             switch (code) {
 548                 case 0x1D:
 549                     state = E1_1D;
 550                     break;
 551                 case 0x9D:
 552                     state = E1_9D;
 553                     break;
 554                 default:
 555                     state = INIT;
 556                     break;
 557             }
 558             break;
 559         case E1_1D:
 560             switch (code) {
 561                 case 0x45:
 562                     matrix_make(0x55);
 563                     break;
 564                 default:
 565                     state = INIT;
 566                     break;
 567             }
 568             break;
 569         case E1_9D:
 570             switch (code) {
 571                 case 0x45:
 572                     matrix_break(0x55);
 573                     break;
 574                 default:
 575                     state = INIT;
 576                     break;
 577             }
 578             break;
 579         default:
 580             state = INIT;
 581     }
 582     return 0;
 583 }
 584
 585
 586 /*******************************************************************************
 587  * AT, PS/2: Scan Code Set 2
 588  *
 589  * Exceptional Handling
 590  * --------------------
 591  * Some keys should be handled exceptionally. See [b].
 592  *
 593  * Scan codes are varied or prefix/postfix'd depending on modifier key state.
 594  *
 595  * 1) Insert, Delete, Home, End, PageUp, PageDown, Up, Down, Right, Left
 596  *     a) when Num Lock is off
 597  *     modifiers | make                      | break
 598  *     ----------+---------------------------+----------------------
 599  *     Ohter     |                    <make> | <break>
 600  *     LShift    | E0 F0 12           <make> | <break>  E0 12
 601  *     RShift    | E0 F0 59           <make> | <break>  E0 59
 602  *     L+RShift  | E0 F0 12  E0 F0 59 <make> | <break>  E0 59 E0 12
 603  *
 604  *     b) when Num Lock is on
 605  *     modifiers | make                      | break
 606  *     ----------+---------------------------+----------------------
 607  *     Other     | E0 12              <make> | <break>  E0 F0 12
 608  *     Shift'd   |                    <make> | <break>
 609  *
 610  *     Handling: These prefix/postfix codes are ignored.
 611  *
 612  *
 613  * 2) Keypad /
 614  *     modifiers | make                      | break
 615  *     ----------+---------------------------+----------------------
 616  *     Ohter     |                    <make> | <break>
 617  *     LShift    | E0 F0 12           <make> | <break>  E0 12
 618  *     RShift    | E0 F0 59           <make> | <break>  E0 59
 619  *     L+RShift  | E0 F0 12  E0 F0 59 <make> | <break>  E0 59 E0 12
 620  *
 621  *     Handling: These prefix/postfix codes are ignored.
 622  *
 623  *
 624  * 3) PrintScreen
 625  *     modifiers | make         | break
 626  *     ----------+--------------+-----------------------------------
 627  *     Other     | E0 12  E0 7C | E0 F0 7C  E0 F0 12
 628  *     Shift'd   |        E0 7C | E0 F0 7C
 629  *     Control'd |        E0 7C | E0 F0 7C
 630  *     Alt'd     |           84 | F0 84
 631  *
 632  *     Handling: These prefix/postfix codes are ignored, and both scan codes
 633  *               'E0 7C' and 84 are seen as PrintScreen.
 634  *
 635  * 4) Pause
 636  *     modifiers | make(no break code)
 637  *     ----------+--------------------------------------------------
 638  *     Other     | E1 14 77 E1 F0 14 F0 77
 639  *     Control'd | E0 7E E0 F0 7E
 640  *
 641  *     Handling: Both code sequences are treated as a whole.
 642  *               And we need a ad hoc 'pseudo break code' hack to get the key off
 643  *               because it has no break code.
 644  *
 645  * Notes:
 646  * 'Hanguel/English'(F1) and 'Hanja'(F2) have no break code. See [a].
 647  * These two Korean keys need exceptional handling and are not supported for now.
 648  *
 649  */
 650 static uint8_t cs2_e0code(uint8_t code) {
 651     switch(code) {
 652         // E0 prefixed codes translation See [a].
 653         case 0x11: return 0x0F; // right alt
 654         case 0x14: return 0x17; // right control
 655         case 0x1F: return 0x19; // left GUI
 656         case 0x27: return 0x1F; // right GUI
 657         case 0x2F: return 0x5C; // apps
 658         case 0x4A: return 0x60; // keypad /
 659         case 0x5A: return 0x62; // keypad enter
 660         case 0x69: return 0x27; // end
 661         case 0x6B: return 0x53; // cursor left
 662         case 0x6C: return 0x2F; // home
 663         case 0x70: return 0x39; // insert
 664         case 0x71: return 0x37; // delete
 665         case 0x72: return 0x3F; // cursor down
 666         case 0x74: return 0x47; // cursor right
 667         case 0x75: return 0x4F; // cursor up
 668         case 0x7A: return 0x56; // page down
 669         case 0x7D: return 0x5E; // page up
 670         case 0x7C: return 0x7F; // Print Screen
 671         case 0x7E: return 0x00; // Control'd Pause
 672
 673         case 0x21: return 0x65; // volume down
 674         case 0x32: return 0x6E; // volume up
 675         case 0x23: return 0x6F; // mute
 676         case 0x10: return 0x08; // (WWW search)     -> F13
 677         case 0x18: return 0x10; // (WWW favourites) -> F14
 678         case 0x20: return 0x18; // (WWW refresh)    -> F15
 679         case 0x28: return 0x20; // (WWW stop)       -> F16
 680         case 0x30: return 0x28; // (WWW forward)    -> F17
 681         case 0x38: return 0x30; // (WWW back)       -> F18
 682         case 0x3A: return 0x38; // (WWW home)       -> F19
 683         case 0x40: return 0x40; // (my computer)    -> F20
 684         case 0x48: return 0x48; // (email)          -> F21
 685         case 0x2B: return 0x50; // (calculator)     -> F22
 686         case 0x34: return 0x08; // (play/pause)     -> F13
 687         case 0x3B: return 0x10; // (stop)           -> F14
 688         case 0x15: return 0x18; // (previous track) -> F15
 689         case 0x4D: return 0x20; // (next track)     -> F16
 690         case 0x50: return 0x28; // (media select)   -> F17
 691         case 0x5E: return 0x50; // (ACPI wake)      -> F22
 692         case 0x3F: return 0x57; // (ACPI sleep)     -> F23
 693         case 0x37: return 0x5F; // (ACPI power)     -> F24
 694
 695         // https://github.com/tmk/tmk_keyboard/pull/636
 696         case 0x03: return 0x18; // Help        DEC LK411 -> F15
 697         case 0x04: return 0x08; // F13         DEC LK411
 698         case 0x0B: return 0x20; // Do          DEC LK411 -> F16
 699         case 0x0C: return 0x10; // F14         DEC LK411
 700         case 0x0D: return 0x19; // LCompose    DEC LK411 -> LGUI
 701         case 0x79: return 0x6D; // KP-         DEC LK411 -> PCMM
 702         case 0x83: return 0x28; // F17         DEC LK411
 703         default: return (code & 0x7F);
 704     }
 705 }
 706
 707 static int8_t process_cs2(uint8_t code)
 708 {
 709     // scan code reading states
 710     static enum {
 711         INIT,
 712         F0,
 713         E0,
 714         E0_F0,
 715         // Pause
 716         E1,
 717         E1_14,
 718         E1_F0,
 719         E1_F0_14,
 720         E1_F0_14_F0,
 721     } state = INIT;
 722
 723     switch (state) {
 724         case INIT:
 725             switch (code) {
 726                 case 0xE0:
 727                     state = E0;
 728                     break;
 729                 case 0xF0:
 730                     state = F0;
 731                     break;
 732                 case 0xE1:
 733                     state = E1;
 734                     break;
 735                 case 0x83:  // F7
 736                     matrix_make(0x02);
 737                     state = INIT;
 738                     break;
 739                 case 0x84:  // Alt'd PrintScreen
 740                     matrix_make(0x7F);
 741                     state = INIT;
 742                     break;
 743                 case 0xAA:  // Self-test passed
 744                 case 0xFC:  // Self-test failed
 745                     // reset or plugin-in new keyboard
 746                     state = INIT;
 747                     return -1;
 748                     break;
 749                 default:    // normal key make
 750                     state = INIT;
 751                     if (code < 0x80) {
 752                         matrix_make(code);
 753                     } else {
 754                         matrix_clear();
 755                         xprintf("!CS2_INIT!\n");
 756                         return -1;
 757                     }
 758             }
 759             break;
 760         case E0:    // E0-Prefixed
 761             switch (code) {
 762                 case 0x12:  // to be ignored
 763                 case 0x59:  // to be ignored
 764                     state = INIT;
 765                     break;
 766                 case 0xF0:
 767                     state = E0_F0;
 768                     break;
 769                 default:
 770                     state = INIT;
 771                     if (code < 0x80) {
 772                         matrix_make(cs2_e0code(code));
 773                     } else {
 774                         matrix_clear();
 775                         xprintf("!CS2_E0!\n");
 776                         return -1;
 777                     }
 778             }
 779             break;
 780         case F0:    // Break code
 781             switch (code) {
 782                 case 0x83:  // F7
 783                     matrix_break(0x02);
 784                     state = INIT;
 785                     break;
 786                 case 0x84:  // Alt'd PrintScreen
 787                     matrix_break(0x7F);
 788                     state = INIT;
 789                     break;
 790                 default:
 791                     state = INIT;
 792                     if (code < 0x80) {
 793                         matrix_break(code);
 794                     } else {
 795                         matrix_clear();
 796                         xprintf("!CS2_F0!\n");
 797                         return -1;
 798                     }
 799             }
 800             break;
 801         case E0_F0: // Break code of E0-prefixed
 802             switch (code) {
 803                 case 0x12:  // to be ignored
 804                 case 0x59:  // to be ignored
 805                     state = INIT;
 806                     break;
 807                 default:
 808                     state = INIT;
 809                     if (code < 0x80) {
 810                         matrix_break(cs2_e0code(code));
 811                     } else {
 812                         matrix_clear();
 813                         xprintf("!CS2_E0_F0!\n");
 814                         return -1;
 815                     }
 816             }
 817             break;
 818         // Pause make: E1 14 77
 819         case E1:
 820             switch (code) {
 821                 case 0x14:
 822                     state = E1_14;
 823                     break;
 824                 case 0xF0:
 825                     state = E1_F0;
 826                     break;
 827                 default:
 828                     state = INIT;
 829             }
 830             break;
 831         case E1_14:
 832             switch (code) {
 833                 case 0x77:
 834                     matrix_make(0x00);
 835                     state = INIT;
 836                     break;
 837                 default:
 838                     state = INIT;
 839             }
 840             break;
 841         // Pause break: E1 F0 14 F0 77
 842         case E1_F0:
 843             switch (code) {
 844                 case 0x14:
 845                     state = E1_F0_14;
 846                     break;
 847                 default:
 848                     state = INIT;
 849             }
 850             break;
 851         case E1_F0_14:
 852             switch (code) {
 853                 case 0xF0:
 854                     state = E1_F0_14_F0;
 855                     break;
 856                 default:
 857                     state = INIT;
 858             }
 859             break;
 860         case E1_F0_14_F0:
 861             switch (code) {
 862                 case 0x77:
 863                     matrix_break(0x00);
 864                     state = INIT;
 865                     break;
 866                 default:
 867                     state = INIT;
 868             }
 869             break;
 870         default:
 871             state = INIT;
 872     }
 873     return 0;
 874 }
 875
 876 /*
 877  * Terminal: Scan Code Set 3
 878  *
 879  * See [3], [7] and
 880  * https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#scan-code-set-3
 881  */
 882 static int8_t process_cs3(uint8_t code)
 883 {
 884     static enum {
 885         READY,
 886         F0,
 887 #ifdef G80_2551_SUPPORT
 888         // G80-2551 four extra keys around cursor keys
 889         G80,
 890         G80_F0,
 891 #endif
 892     } state = READY;
 893
 894     switch (state) {
 895         case READY:
 896             switch (code) {
 897                 case 0xF0:
 898                     state = F0;
 899                     break;
 900                 case 0x83:  // PrintScreen
 901                     matrix_make(0x02);
 902                     break;
 903                 case 0x84:  // Keypad *
 904                     matrix_make(0x7F);
 905                     break;
 906                 case 0x85:  // Muhenkan
 907                     matrix_make(0x0B);
 908                     break;
 909                 case 0x86:  // Henkan
 910                     matrix_make(0x06);
 911                     break;
 912                 case 0x87:  // Hiragana
 913                     matrix_make(0x00);
 914                     break;
 915                 case 0x8B:  // Left GUI
 916                     matrix_make(0x01);
 917                     break;
 918                 case 0x8C:  // Right GUI
 919                     matrix_make(0x09);
 920                     break;
 921                 case 0x8D:  // Application
 922                     matrix_make(0x0A);
 923                     break;
 924 #ifdef G80_2551_SUPPORT
 925                 case 0x80:  // G80-2551 four extra keys around cursor keys
 926                     state = G80;
 927                     break;
 928 #endif
 929                 default:    // normal key make
 930                     if (code < 0x80) {
 931                         matrix_make(code);
 932                     } else {
 933                         xprintf("!CS3_READY!\n");
 934                         //return -1;
 935                     }
 936             }
 937             break;
 938         case F0:    // Break code
 939             switch (code) {
 940                 case 0x83:  // PrintScreen
 941                     matrix_break(0x02);
 942                     state = READY;
 943                     break;
 944                 case 0x84:  // Keypad *
 945                     matrix_break(0x7F);
 946                     state = READY;
 947                     break;
 948                 case 0x85:  // Muhenkan
 949                     matrix_break(0x0B);
 950                     state = READY;
 951                     break;
 952                 case 0x86:  // Henkan
 953                     matrix_break(0x06);
 954                     state = READY;
 955                     break;
 956                 case 0x87:  // Hiragana
 957                     matrix_break(0x00);
 958                     state = READY;
 959                     break;
 960                 case 0x8B:  // Left GUI
 961                     matrix_break(0x01);
 962                     state = READY;
 963                     break;
 964                 case 0x8C:  // Right GUI
 965                     matrix_break(0x09);
 966                     state = READY;
 967                     break;
 968                 case 0x8D:  // Application
 969                     matrix_break(0x0A);
 970                     state = READY;
 971                     break;
 972                 default:
 973                     state = READY;
 974                     if (code < 0x80) {
 975                         matrix_break(code);
 976                     } else {
 977                         xprintf("!CS3_F0!\n");
 978                         //return -1;
 979                     }
 980             }
 981             break;
 982 #ifdef G80_2551_SUPPORT
 983         /*
 984          * G80-2551 terminal keyboard support
 985          * https://deskthority.net/wiki/Cherry_G80-2551
 986          * https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#g80-2551-in-code-set-3
 987          */
 988         case G80:   // G80-2551 four extra keys around cursor keys
 989             switch (code) {
 990                 case (0x26):    // TD= -> JYEN
 991                     matrix_make(0x5D);
 992                     break;
 993                 case (0x25):    // page with edge -> NUHS
 994                     matrix_make(0x53);
 995                     break;
 996                 case (0x16):    // two pages -> RO
 997                     matrix_make(0x51);
 998                     break;
 999                 case (0x1E):    // calc -> KANA
1000                     matrix_make(0x00);
1001                     break;
1002                 case (0xF0):
1003                     state = G80_F0;
1004                     return 0;
1005                 default:
1006                     // Not supported
1007                     matrix_clear();
1008                     break;
1009             }
1010             state = READY;
1011             break;
1012         case G80_F0:
1013             switch (code) {
1014                 case (0x26):    // TD= -> JYEN
1015                     matrix_break(0x5D);
1016                     break;
1017                 case (0x25):    // page with edge -> NUHS
1018                     matrix_break(0x53);
1019                     break;
1020                 case (0x16):    // two pages -> RO
1021                     matrix_break(0x51);
1022                     break;
1023                 case (0x1E):    // calc -> KANA
1024                     matrix_break(0x00);
1025                     break;
1026                 default:
1027                     // Not supported
1028                     matrix_clear();
1029                     break;
1030             }
1031             state = READY;
1032             break;
1033 #endif
1034     }
1035     return 0;
1036 }
1037
1038 /*
1039  * IBM PC Keyboard Protocol Resources:
1040  *
1041  * [a] Microsoft USB HID to PS/2 Translation Table - Scan Code Set 1 and 2
1042  * http://download.microsoft.com/download/1/6/1/161ba512-40e2-4cc9-843a-923143f3456c/translate.pdf
1043  *
1044  * [b] Microsoft Keyboard Scan Code Specification - Special rules of Scan Code Set 1 and 2
1045  * http://download.microsoft.com/download/1/6/1/161ba512-40e2-4cc9-843a-923143f3456c/scancode.doc
1046  *
1047  * [1] PS/2 Reference Manuals - Collection of IBM Personal System/2 documents.
1048  * http://www.mcamafia.de/pdf/pdfref.htm
1049  *
1050  * [2] Keyboard and Auxiliary Device Controller - Signal Timing and Format
1051  * http://www.mcamafia.de/pdf/ibm_hitrc07.pdf
1052  *
1053  * [3] Keyboards(101- and 102-key) - Keyboard Layout, Scan Code Set, POR, and Commands.
1054  * http://www.mcamafia.de/pdf/ibm_hitrc11.pdf
1055  *
1056  * [4] IBM PC XT Keyboard Protocol
1057  * https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-XT-Keyboard-Protocol
1058  *
1059  * [5] IBM Keyboard Scan Code by John Elliott - 83-key, 84-key, 102-key and 122-key
1060  * https://www.seasip.info/VintagePC/index.html
1061  *
1062  * [6] IBM 1391406 Keyboard - Scan Code Set 2 of 102-key PS/2 keyboard
1063  * https://www.seasip.info/VintagePC/ibm_1391406.html
1064  *
1065  * [7] The IBM 6110344 Keyboard - Scan Code Set 3 of 122-key terminal keyboard
1066  * https://www.seasip.info/VintagePC/ibm_6110344.html
1067  *
1068  * [8] IBM PC AT Technical Reference 1986
1069  * http://bitsavers.org/pdf/ibm/pc/at/6183355_PC_AT_Technical_Reference_Mar86.pdf
1070  *
1071  * [y] TrackPoint Engineering Specifications for version 3E
1072  * https://web.archive.org/web/20100526161812/http://wwwcssrv.almaden.ibm.com/trackpoint/download.html
1073  *
1074  * [z] [Soarer's XT/AT/PS2/Terminal to USB converter]
1075  * https://geekhack.org/index.php?topic=17458.0
1076  *
1077  */