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         WAIT_SETTLE,
 117         AT_RESET,
 118         XT_RESET,
 119         XT_RESET_WAIT,
 120         XT_RESET_DONE,
 121         WAIT_AA,
 122         WAIT_AABF,
 123         WAIT_AABFBF,
 124         READ_ID,
 125         SETUP,
 126         LOOP,
 127     } state = INIT;
 128     static uint16_t init_time;
 129
 130
 131     if (ibmpc_error) {
 132         xprintf("\nERR:%02X ISR:%04X ", ibmpc_error, ibmpc_isr_debug);
 133
 134         // when recv error, neither send error nor buffer full
 135         if (!(ibmpc_error & (IBMPC_ERR_SEND | IBMPC_ERR_FULL))) {
 136             // keyboard init again
 137             if (state == LOOP) {
 138                 xprintf("[RST] ");
 139                 state = INIT;
 140             }
 141         }
 142
 143         // clear or process error
 144         ibmpc_error = IBMPC_ERR_NONE;
 145         ibmpc_isr_debug = 0;
 146     }
 147
 148     // check protocol change AT/XT
 149     if (ibmpc_protocol && ibmpc_protocol != current_protocol) {
 150         xprintf("\nPRT:%02X ISR:%04X ", ibmpc_protocol, ibmpc_isr_debug);
 151
 152         // protocol change between AT and XT indicates that
 153         // keyboard is hotswapped or something goes wrong.
 154         // This requires initializing keyboard again probably.
 155         if (((current_protocol&IBMPC_PROTOCOL_XT) && (ibmpc_protocol&IBMPC_PROTOCOL_AT)) ||
 156             ((current_protocol&IBMPC_PROTOCOL_AT) && (ibmpc_protocol&IBMPC_PROTOCOL_XT))) {
 157             if (state == LOOP) {
 158                 xprintf("[CHG] ");
 159                 state = INIT;
 160             }
 161         }
 162
 163         current_protocol = ibmpc_protocol;
 164         ibmpc_isr_debug = 0;
 165     }
 166
 167     switch (state) {
 168         case INIT:
 169             ibmpc_host_disable();
 170
 171             xprintf("I%u ", timer_read());
 172             keyboard_kind = NONE;
 173             keyboard_id = 0x0000;
 174
 175             matrix_clear();
 176             clear_keyboard();
 177
 178             init_time = timer_read();
 179             state = WAIT_SETTLE;
 180             break;
 181         case WAIT_SETTLE:
 182             // wait for keyboard to settle after plugin
 183             if (timer_elapsed(init_time) > 1000) {
 184                 state = AT_RESET;
 185             }
 186             break;
 187         case AT_RESET:
 188             ibmpc_host_isr_clear();
 189             ibmpc_host_enable();
 190             wait_ms(1); // keyboard can't respond to command without this
 191
 192             // SKIDATA-2-DE(and some other keyboards?) stores 'Code Set' setting in nonvlatile memory
 193             // and keeps it until receiving reset. Sending reset here may be useful to clear it, perhaps.
 194             // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#select-alternate-scan-codesf0
 195
 196             // reset command
 197             if (0xFA == ibmpc_host_send(0xFF)) {
 198                 state = WAIT_AA;
 199             } else {
 200                 state = XT_RESET;
 201             }
 202             xprintf("A%u ", timer_read());
 203             break;
 204         case XT_RESET:
 205             // Reset XT-initialize keyboard
 206             // XT: hard reset 500ms for IBM XT Type-1 keyboard and clones
 207             // XT: soft reset 20ms min
 208             // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-XT-Keyboard-Protocol#keyboard-soft-reset
 209             ibmpc_host_disable();   // soft reset: Clock Lo/Data Hi
 210             IBMPC_RST_LO();         // hard reset: Reset pin Lo
 211
 212             init_time = timer_read();
 213             state = XT_RESET_WAIT;
 214             break;
 215         case XT_RESET_WAIT:
 216             if (timer_elapsed(init_time) > 500) {
 217                 state = XT_RESET_DONE;
 218             }
 219             break;
 220         case XT_RESET_DONE:
 221             IBMPC_RST_HIZ();        // hard reset: Reset pin HiZ
 222             ibmpc_host_isr_clear();
 223             ibmpc_host_enable();    // soft reset: idle(Clock Hi/Data Hi)
 224
 225             xprintf("X%u ", timer_read());
 226             init_time = timer_read();
 227             state = WAIT_AA;
 228             break;
 229         case WAIT_AA:
 230             // 1) Read BAT code and ID on keybaord power-up
 231             // For example, XT/AT sends 'AA' and Terminal sends 'AA BF BF' after BAT
 232             // AT 84-key: POR and BAT can take 900-9900ms according to AT TechRef [8] 4-7
 233             // AT 101/102-key: POR and BAT can take 450-2500ms according to AT TechRef [8] 4-39
 234             // 2) Read key typed by user or anything after error on protocol or scan code
 235             // This can happen in case of keyboard hotswap, unstable hardware, signal integrity problem or bug
 236
 237             /* wait until keyboard sends any code without 10000ms timeout
 238             if (timer_elapsed(init_time) > 10000) {
 239                 state = READ_ID;
 240             }
 241             */
 242             if (ibmpc_host_recv() != -1) {  // wait for AA
 243                 xprintf("W%u ", timer_read());
 244                 init_time = timer_read();
 245                 state = WAIT_AABF;
 246             }
 247             break;
 248         case WAIT_AABF:
 249             // NOTE: we can omit to wait BF BF
 250             // ID takes 500ms max? TechRef [8] 4-41, though 1ms is enough for 122-key Terminal 6110345
 251             if (timer_elapsed(init_time) > 500) {
 252                 state = READ_ID;
 253             }
 254             if (ibmpc_host_recv() != -1) {  // wait for BF
 255                 xprintf("W%u ", timer_read());
 256                 init_time = timer_read();
 257                 state = WAIT_AABFBF;
 258             }
 259             break;
 260         case WAIT_AABFBF:
 261             if (timer_elapsed(init_time) > 500) {
 262                 state = READ_ID;
 263             }
 264             if (ibmpc_host_recv() != -1) {  // wait for BF
 265                 xprintf("W%u ", timer_read());
 266                 state = READ_ID;
 267             }
 268             break;
 269         case READ_ID:
 270             keyboard_id = read_keyboard_id();
 271             xprintf("R%u ", timer_read());
 272
 273             if (0x0000 == keyboard_id) {            // CodeSet2 AT(IBM PC AT 84-key)
 274                 keyboard_kind = PC_AT;
 275             } else if (0xFFFF == keyboard_id) {     // CodeSet1 XT
 276                 keyboard_kind = PC_XT;
 277             } else if (0xFFFE == keyboard_id) {     // CodeSet2 PS/2 fails to response?
 278                 keyboard_kind = PC_AT;
 279             } else if (0x00FF == keyboard_id) {     // Mouse is not supported
 280                 xprintf("Mouse: not supported\n");
 281                 keyboard_kind = NONE;
 282 #ifdef G80_2551_SUPPORT
 283             } else if (0xAB86 == keyboard_id ||
 284                        0xAB85 == keyboard_id) {     // For G80-2551 and other 122-key terminal
 285                 // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#ab86
 286                 // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#ab85
 287
 288                 if ((0xFA == ibmpc_host_send(0xF0)) &&
 289                     (0xFA == ibmpc_host_send(0x03))) {
 290                     // switch to code set 3
 291                     keyboard_kind = PC_TERMINAL;
 292                 } else {
 293                     keyboard_kind = PC_AT;
 294                 }
 295 #endif
 296             } else if (0xBFB0 == keyboard_id) {     // IBM RT Keyboard
 297                 // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#bfb0
 298                 // TODO: LED indicator fix
 299                 //keyboard_kind = PC_TERMINAL_IBM_RT;
 300                 keyboard_kind = PC_TERMINAL;
 301             } else if (0xAB00 == (keyboard_id & 0xFF00)) {  // CodeSet2 PS/2
 302                 keyboard_kind = PC_AT;
 303             } else if (0xBF00 == (keyboard_id & 0xFF00)) {  // CodeSet3 Terminal
 304                 keyboard_kind = PC_TERMINAL;
 305             } else {
 306                 keyboard_kind = PC_AT;
 307             }
 308
 309             xprintf("\nID:%04X(%d) ", keyboard_id, keyboard_kind);
 310
 311             state = SETUP;
 312             break;
 313         case SETUP:
 314             xprintf("S%u ", timer_read());
 315             switch (keyboard_kind) {
 316                 case PC_XT:
 317                     break;
 318                 case PC_AT:
 319                     led_set(host_keyboard_leds());
 320                     break;
 321                 case PC_TERMINAL:
 322                     // Set all keys to make/break type
 323                     ibmpc_host_send(0xF8);
 324                     // This should not be harmful
 325                     led_set(host_keyboard_leds());
 326                     break;
 327                 default:
 328                     break;
 329             }
 330             state = LOOP;
 331             xprintf("L%u ", timer_read());
 332         case LOOP:
 333             {
 334                 uint16_t code = ibmpc_host_recv();
 335                 if (code == -1) {
 336                     // no code
 337                     break;
 338                 }
 339
 340                 // Keyboard Error/Overrun([3]p.26) or Buffer full
 341                 // Scan Code Set 1: 0xFF
 342                 // Scan Code Set 2 and 3: 0x00
 343                 // Buffer full(IBMPC_ERR_FULL): 0xFF
 344                 if (code == 0x00 || code == 0xFF) {
 345                     // clear stuck keys
 346                     matrix_clear();
 347                     clear_keyboard();
 348
 349                     xprintf("\n[OVR] ");
 350                     break;
 351                 }
 352
 353                 switch (keyboard_kind) {
 354                     case PC_XT:
 355                         if (process_cs1(code) == -1) state = INIT;
 356                         break;
 357                     case PC_AT:
 358                         if (process_cs2(code) == -1) state = INIT;
 359                         break;
 360                     case PC_TERMINAL:
 361                         if (process_cs3(code) == -1) state = INIT;
 362                         break;
 363                     default:
 364                         break;
 365                 }
 366             }
 367             break;
 368         default:
 369             break;
 370     }
 371     return 1;
 372 }
 373
 374 inline
 375 bool matrix_is_on(uint8_t row, uint8_t col)
 376 {
 377     return (matrix[row] & (1<<col));
 378 }
 379
 380 inline
 381 uint8_t matrix_get_row(uint8_t row)
 382 {
 383     return matrix[row];
 384 }
 385
 386 uint8_t matrix_key_count(void)
 387 {
 388     uint8_t count = 0;
 389     for (uint8_t i = 0; i < MATRIX_ROWS; i++) {
 390         count += bitpop(matrix[i]);
 391     }
 392     return count;
 393 }
 394
 395
 396 inline
 397 static void matrix_make(uint8_t code)
 398 {
 399     if (!matrix_is_on(ROW(code), COL(code))) {
 400         matrix[ROW(code)] |= 1<<COL(code);
 401     }
 402 }
 403
 404 inline
 405 static void matrix_break(uint8_t code)
 406 {
 407     if (matrix_is_on(ROW(code), COL(code))) {
 408         matrix[ROW(code)] &= ~(1<<COL(code));
 409     }
 410 }
 411
 412 void matrix_clear(void)
 413 {
 414     for (uint8_t i=0; i < MATRIX_ROWS; i++) matrix[i] = 0x00;
 415 }
 416
 417 void led_set(uint8_t usb_led)
 418 {
 419     // Sending before keyboard recognition may be harmful for XT keyboard
 420     if (keyboard_kind == NONE) return;
 421
 422     // XT keyobard doesn't support any command and it is harmful perhaps
 423     // https://github.com/tmk/tmk_keyboard/issues/635#issuecomment-626993437
 424     if (keyboard_kind == PC_XT) return;
 425
 426     // It should be safe to send the command to keyboards with AT protocol
 427     // - IBM Terminal doesn't support the command and response with 0xFE but it is not harmful.
 428     // - Some other Terminals like G80-2551 supports the command.
 429     //   https://geekhack.org/index.php?topic=103648.msg2894921#msg2894921
 430
 431     // TODO: PC_TERMINAL_IBM_RT support
 432     uint8_t ibmpc_led = 0;
 433     if (usb_led &  (1<<USB_LED_SCROLL_LOCK))
 434         ibmpc_led |= (1<<IBMPC_LED_SCROLL_LOCK);
 435     if (usb_led &  (1<<USB_LED_NUM_LOCK))
 436         ibmpc_led |= (1<<IBMPC_LED_NUM_LOCK);
 437     if (usb_led &  (1<<USB_LED_CAPS_LOCK))
 438         ibmpc_led |= (1<<IBMPC_LED_CAPS_LOCK);
 439     ibmpc_host_set_led(ibmpc_led);
 440 }
 441
 442
 443 /*******************************************************************************
 444  * XT: Scan Code Set 1
 445  *
 446  * See [3], [a]
 447  *
 448  * E0-escaped scan codes are translated into unused range of the matrix.(54-7F)
 449  *
 450  *     01-53: Normal codes used in original XT keyboard
 451  *     54-7F: Not used in original XT keyboard
 452  *
 453  *         0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
 454  *     50  -   -   -   -   *   *   x   x   x   x   *   *   *   *   *   *
 455  *     60  *   *   *   *   x   x   x   x   x   x   x   x   x   x   x   *
 456  *     70  x   *   *   x   *   *   x   *   *   x   *   x   *   x   x   *
 457  *
 458  * -: codes existed in original XT keyboard
 459  * *: E0-escaped codes translated
 460  * x: Non-espcaped codes(Some are not used in real keyboards probably)
 461  *
 462  * Codes assigned in range 54-7F:
 463  *
 464  *     50  -                60  Up*                 70  KANAx
 465  *     51  -                61  Left*               71  Insert*
 466  *     52  -                62  Down*               72  Delete*
 467  *     53  -                63  Right*              73  ROx
 468  *     54  PrintScr*        64  F13x                74  Home*
 469  *     55  Pause*           65  F14x                75  End*
 470  *     56  Euro2x           66  F15x                76  F24x
 471  *     57  F11x             67  F16x                77  PageUp*
 472  *     58  F12x             68  F17x                78  PageDown*
 473  *     59  Keypad=x         69  F18x                79  HENKANx
 474  *     5A  LGUI*            6A  F19x                7A  RCTL*
 475  *     5B  RGUI*            6B  F20x                7B  MUHENKANx
 476  *     5C  APP*             6C  F21x                7C  RALT*
 477  *     5D  Mute*            6D  F22x                7D  JPYx
 478  *     5E  Volume Down*     6E  F23x                7E  Keypad,x
 479  *     5F  Volume Up*       6F  Keypad Enter*       7F  Keypad/ *
 480  */
 481 static uint8_t cs1_e0code(uint8_t code) {
 482     switch(code) {
 483         // Original IBM XT keyboard doesn't use E0-codes probably
 484         // Some XT compatilble keyobards need these keys?
 485         case 0x37: return 0x54; // Print Screen
 486         case 0x46: return 0x55; // Ctrl + Pause
 487         case 0x5B: return 0x5A; // Left  GUI
 488         case 0x5C: return 0x5B; // Right GUI
 489         case 0x5D: return 0x5C; // Application
 490         case 0x20: return 0x5D; // Mute
 491         case 0x2E: return 0x5E; // Volume Down
 492         case 0x30: return 0x5F; // Volume Up
 493         case 0x48: return 0x60; // Up
 494         case 0x4B: return 0x61; // Left
 495         case 0x50: return 0x62; // Down
 496         case 0x4D: return 0x63; // Right
 497         case 0x1C: return 0x6F; // Keypad Enter
 498         case 0x52: return 0x71; // Insert
 499         case 0x53: return 0x72; // Delete
 500         case 0x47: return 0x74; // Home
 501         case 0x4F: return 0x75; // End
 502         case 0x49: return 0x77; // Page Up
 503         case 0x51: return 0x78; // Page Down
 504         case 0x1D: return 0x7A; // Right Ctrl
 505         case 0x38: return 0x7C; // Right Alt
 506         case 0x35: return 0x7F; // Keypad /
 507
 508         // Shared matrix cell with other keys
 509         case 0x5E: return 0x70; // Power (KANA)
 510         case 0x5F: return 0x79; // Sleep (HENKAN)
 511         case 0x63: return 0x7B; // Wake  (MUHENKAN)
 512
 513         default:
 514            xprintf("!CS1_E0_%02X!\n", code);
 515            return code;
 516     }
 517     return 0x00;
 518 }
 519
 520 static int8_t process_cs1(uint8_t code)
 521 {
 522     static enum {
 523         INIT,
 524         E0,
 525         // Pause: E1 1D 45, E1 9D C5 [a]
 526         E1,
 527         E1_1D,
 528         E1_9D,
 529     } state = INIT;
 530
 531     switch (state) {
 532         case INIT:
 533             switch (code) {
 534                 case 0xE0:
 535                     state = E0;
 536                     break;
 537                 case 0xE1:
 538                     state = E1;
 539                     break;
 540                 default:
 541                     if (code < 0x80)
 542                         matrix_make(code);
 543                     else
 544                         matrix_break(code & 0x7F);
 545                     break;
 546             }
 547             break;
 548         case E0:
 549             switch (code) {
 550                 case 0x2A:
 551                 case 0xAA:
 552                 case 0x36:
 553                 case 0xB6:
 554                     //ignore fake shift
 555                     state = INIT;
 556                     break;
 557                 default:
 558                     if (code < 0x80)
 559                         matrix_make(cs1_e0code(code));
 560                     else
 561                         matrix_break(cs1_e0code(code & 0x7F));
 562                     state = INIT;
 563                     break;
 564             }
 565             break;
 566         case E1:
 567             switch (code) {
 568                 case 0x1D:
 569                     state = E1_1D;
 570                     break;
 571                 case 0x9D:
 572                     state = E1_9D;
 573                     break;
 574                 default:
 575                     state = INIT;
 576                     break;
 577             }
 578             break;
 579         case E1_1D:
 580             switch (code) {
 581                 case 0x45:
 582                     matrix_make(0x55); // Pause
 583                     state = INIT;
 584                     break;
 585                 default:
 586                     state = INIT;
 587                     break;
 588             }
 589             break;
 590         case E1_9D:
 591             switch (code) {
 592                 case 0xC5:
 593                     matrix_break(0x55); // Pause
 594                     state = INIT;
 595                     break;
 596                 default:
 597                     state = INIT;
 598                     break;
 599             }
 600             break;
 601         default:
 602             state = INIT;
 603     }
 604     return 0;
 605 }
 606
 607
 608 /*******************************************************************************
 609  * AT, PS/2: Scan Code Set 2
 610  *
 611  * Exceptional Handling
 612  * --------------------
 613  * Some keys should be handled exceptionally. See [b].
 614  *
 615  * Scan codes are varied or prefix/postfix'd depending on modifier key state.
 616  *
 617  * 1) Insert, Delete, Home, End, PageUp, PageDown, Up, Down, Right, Left
 618  *     a) when Num Lock is off
 619  *     modifiers | make                      | break
 620  *     ----------+---------------------------+----------------------
 621  *     Ohter     |                    <make> | <break>
 622  *     LShift    | E0 F0 12           <make> | <break>  E0 12
 623  *     RShift    | E0 F0 59           <make> | <break>  E0 59
 624  *     L+RShift  | E0 F0 12  E0 F0 59 <make> | <break>  E0 59 E0 12
 625  *
 626  *     b) when Num Lock is on
 627  *     modifiers | make                      | break
 628  *     ----------+---------------------------+----------------------
 629  *     Other     | E0 12              <make> | <break>  E0 F0 12
 630  *     Shift'd   |                    <make> | <break>
 631  *
 632  *     Handling: These prefix/postfix codes are ignored.
 633  *
 634  *
 635  * 2) Keypad /
 636  *     modifiers | make                      | break
 637  *     ----------+---------------------------+----------------------
 638  *     Ohter     |                    <make> | <break>
 639  *     LShift    | E0 F0 12           <make> | <break>  E0 12
 640  *     RShift    | E0 F0 59           <make> | <break>  E0 59
 641  *     L+RShift  | E0 F0 12  E0 F0 59 <make> | <break>  E0 59 E0 12
 642  *
 643  *     Handling: These prefix/postfix codes are ignored.
 644  *
 645  *
 646  * 3) PrintScreen
 647  *     modifiers | make         | break
 648  *     ----------+--------------+-----------------------------------
 649  *     Other     | E0 12  E0 7C | E0 F0 7C  E0 F0 12
 650  *     Shift'd   |        E0 7C | E0 F0 7C
 651  *     Control'd |        E0 7C | E0 F0 7C
 652  *     Alt'd     |           84 | F0 84
 653  *
 654  *     Handling: These prefix/postfix codes are ignored, and both scan codes
 655  *               'E0 7C' and 84 are seen as PrintScreen.
 656  *
 657  * 4) Pause
 658  *     modifiers | make(no break code)
 659  *     ----------+--------------------------------------------------
 660  *     Other     | E1 14 77 E1 F0 14 F0 77
 661  *     Control'd | E0 7E E0 F0 7E
 662  *
 663  *     Handling: Both code sequences are treated as a whole.
 664  *               And we need a ad hoc 'pseudo break code' hack to get the key off
 665  *               because it has no break code.
 666  *
 667  * Notes:
 668  * 'Hanguel/English'(F1) and 'Hanja'(F2) have no break code. See [a].
 669  * These two Korean keys need exceptional handling and are not supported for now.
 670  *
 671  */
 672 static uint8_t cs2_e0code(uint8_t code) {
 673     switch(code) {
 674         // E0 prefixed codes translation See [a].
 675         case 0x11: return 0x0F; // right alt
 676         case 0x14: return 0x17; // right control
 677         case 0x1F: return 0x19; // left GUI
 678         case 0x27: return 0x1F; // right GUI
 679         case 0x2F: return 0x5C; // apps
 680         case 0x4A: return 0x60; // keypad /
 681         case 0x5A: return 0x62; // keypad enter
 682         case 0x69: return 0x27; // end
 683         case 0x6B: return 0x53; // cursor left
 684         case 0x6C: return 0x2F; // home
 685         case 0x70: return 0x39; // insert
 686         case 0x71: return 0x37; // delete
 687         case 0x72: return 0x3F; // cursor down
 688         case 0x74: return 0x47; // cursor right
 689         case 0x75: return 0x4F; // cursor up
 690         case 0x7A: return 0x56; // page down
 691         case 0x7D: return 0x5E; // page up
 692         case 0x7C: return 0x7F; // Print Screen
 693         case 0x7E: return 0x00; // Control'd Pause
 694
 695         case 0x21: return 0x65; // volume down
 696         case 0x32: return 0x6E; // volume up
 697         case 0x23: return 0x6F; // mute
 698         case 0x10: return 0x08; // (WWW search)     -> F13
 699         case 0x18: return 0x10; // (WWW favourites) -> F14
 700         case 0x20: return 0x18; // (WWW refresh)    -> F15
 701         case 0x28: return 0x20; // (WWW stop)       -> F16
 702         case 0x30: return 0x28; // (WWW forward)    -> F17
 703         case 0x38: return 0x30; // (WWW back)       -> F18
 704         case 0x3A: return 0x38; // (WWW home)       -> F19
 705         case 0x40: return 0x40; // (my computer)    -> F20
 706         case 0x48: return 0x48; // (email)          -> F21
 707         case 0x2B: return 0x50; // (calculator)     -> F22
 708         case 0x34: return 0x08; // (play/pause)     -> F13
 709         case 0x3B: return 0x10; // (stop)           -> F14
 710         case 0x15: return 0x18; // (previous track) -> F15
 711         case 0x4D: return 0x20; // (next track)     -> F16
 712         case 0x50: return 0x28; // (media select)   -> F17
 713         case 0x5E: return 0x50; // (ACPI wake)      -> F22
 714         case 0x3F: return 0x57; // (ACPI sleep)     -> F23
 715         case 0x37: return 0x5F; // (ACPI power)     -> F24
 716
 717         // https://github.com/tmk/tmk_keyboard/pull/636
 718         case 0x03: return 0x18; // Help        DEC LK411 -> F15
 719         case 0x04: return 0x08; // F13         DEC LK411
 720         case 0x0B: return 0x20; // Do          DEC LK411 -> F16
 721         case 0x0C: return 0x10; // F14         DEC LK411
 722         case 0x0D: return 0x19; // LCompose    DEC LK411 -> LGUI
 723         case 0x79: return 0x6D; // KP-         DEC LK411 -> PCMM
 724         case 0x83: return 0x28; // F17         DEC LK411
 725         default: return (code & 0x7F);
 726     }
 727 }
 728
 729 static int8_t process_cs2(uint8_t code)
 730 {
 731     // scan code reading states
 732     static enum {
 733         INIT,
 734         F0,
 735         E0,
 736         E0_F0,
 737         // Pause
 738         E1,
 739         E1_14,
 740         E1_F0,
 741         E1_F0_14,
 742         E1_F0_14_F0,
 743     } state = INIT;
 744
 745     switch (state) {
 746         case INIT:
 747             switch (code) {
 748                 case 0xE0:
 749                     state = E0;
 750                     break;
 751                 case 0xF0:
 752                     state = F0;
 753                     break;
 754                 case 0xE1:
 755                     state = E1;
 756                     break;
 757                 case 0x83:  // F7
 758                     matrix_make(0x02);
 759                     state = INIT;
 760                     break;
 761                 case 0x84:  // Alt'd PrintScreen
 762                     matrix_make(0x7F);
 763                     state = INIT;
 764                     break;
 765                 case 0xAA:  // Self-test passed
 766                 case 0xFC:  // Self-test failed
 767                     // replug or unstable connection probably
 768                 default:    // normal key make
 769                     state = INIT;
 770                     if (code < 0x80) {
 771                         matrix_make(code);
 772                     } else {
 773                         matrix_clear();
 774                         xprintf("!CS2_INIT!\n");
 775                         return -1;
 776                     }
 777             }
 778             break;
 779         case E0:    // E0-Prefixed
 780             switch (code) {
 781                 case 0x12:  // to be ignored
 782                 case 0x59:  // to be ignored
 783                     state = INIT;
 784                     break;
 785                 case 0xF0:
 786                     state = E0_F0;
 787                     break;
 788                 default:
 789                     state = INIT;
 790                     if (code < 0x80) {
 791                         matrix_make(cs2_e0code(code));
 792                     } else {
 793                         matrix_clear();
 794                         xprintf("!CS2_E0!\n");
 795                         return -1;
 796                     }
 797             }
 798             break;
 799         case F0:    // Break code
 800             switch (code) {
 801                 case 0x83:  // F7
 802                     matrix_break(0x02);
 803                     state = INIT;
 804                     break;
 805                 case 0x84:  // Alt'd PrintScreen
 806                     matrix_break(0x7F);
 807                     state = INIT;
 808                     break;
 809                 default:
 810                     state = INIT;
 811                     if (code < 0x80) {
 812                         matrix_break(code);
 813                     } else {
 814                         matrix_clear();
 815                         xprintf("!CS2_F0!\n");
 816                         return -1;
 817                     }
 818             }
 819             break;
 820         case E0_F0: // Break code of E0-prefixed
 821             switch (code) {
 822                 case 0x12:  // to be ignored
 823                 case 0x59:  // to be ignored
 824                     state = INIT;
 825                     break;
 826                 default:
 827                     state = INIT;
 828                     if (code < 0x80) {
 829                         matrix_break(cs2_e0code(code));
 830                     } else {
 831                         matrix_clear();
 832                         xprintf("!CS2_E0_F0!\n");
 833                         return -1;
 834                     }
 835             }
 836             break;
 837         // Pause make: E1 14 77
 838         case E1:
 839             switch (code) {
 840                 case 0x14:
 841                     state = E1_14;
 842                     break;
 843                 case 0xF0:
 844                     state = E1_F0;
 845                     break;
 846                 default:
 847                     state = INIT;
 848             }
 849             break;
 850         case E1_14:
 851             switch (code) {
 852                 case 0x77:
 853                     matrix_make(0x00);
 854                     state = INIT;
 855                     break;
 856                 default:
 857                     state = INIT;
 858             }
 859             break;
 860         // Pause break: E1 F0 14 F0 77
 861         case E1_F0:
 862             switch (code) {
 863                 case 0x14:
 864                     state = E1_F0_14;
 865                     break;
 866                 default:
 867                     state = INIT;
 868             }
 869             break;
 870         case E1_F0_14:
 871             switch (code) {
 872                 case 0xF0:
 873                     state = E1_F0_14_F0;
 874                     break;
 875                 default:
 876                     state = INIT;
 877             }
 878             break;
 879         case E1_F0_14_F0:
 880             switch (code) {
 881                 case 0x77:
 882                     matrix_break(0x00);
 883                     state = INIT;
 884                     break;
 885                 default:
 886                     state = INIT;
 887             }
 888             break;
 889         default:
 890             state = INIT;
 891     }
 892     return 0;
 893 }
 894
 895 /*
 896  * Terminal: Scan Code Set 3
 897  *
 898  * See [3], [7] and
 899  * https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#scan-code-set-3
 900  */
 901 static int8_t process_cs3(uint8_t code)
 902 {
 903     static enum {
 904         READY,
 905         F0,
 906 #ifdef G80_2551_SUPPORT
 907         // G80-2551 four extra keys around cursor keys
 908         G80,
 909         G80_F0,
 910 #endif
 911     } state = READY;
 912
 913     switch (state) {
 914         case READY:
 915             switch (code) {
 916                 case 0xF0:
 917                     state = F0;
 918                     break;
 919                 case 0x83:  // PrintScreen
 920                     matrix_make(0x02);
 921                     break;
 922                 case 0x84:  // Keypad *
 923                     matrix_make(0x7F);
 924                     break;
 925                 case 0x85:  // Muhenkan
 926                     matrix_make(0x0B);
 927                     break;
 928                 case 0x86:  // Henkan
 929                     matrix_make(0x06);
 930                     break;
 931                 case 0x87:  // Hiragana
 932                     matrix_make(0x00);
 933                     break;
 934                 case 0x8B:  // Left GUI
 935                     matrix_make(0x01);
 936                     break;
 937                 case 0x8C:  // Right GUI
 938                     matrix_make(0x09);
 939                     break;
 940                 case 0x8D:  // Application
 941                     matrix_make(0x0A);
 942                     break;
 943 #ifdef G80_2551_SUPPORT
 944                 case 0x80:  // G80-2551 four extra keys around cursor keys
 945                     state = G80;
 946                     break;
 947 #endif
 948                 default:    // normal key make
 949                     if (code < 0x80) {
 950                         matrix_make(code);
 951                     } else {
 952                         xprintf("!CS3_READY!\n");
 953                         return -1;
 954                     }
 955             }
 956             break;
 957         case F0:    // Break code
 958             switch (code) {
 959                 case 0x83:  // PrintScreen
 960                     matrix_break(0x02);
 961                     state = READY;
 962                     break;
 963                 case 0x84:  // Keypad *
 964                     matrix_break(0x7F);
 965                     state = READY;
 966                     break;
 967                 case 0x85:  // Muhenkan
 968                     matrix_break(0x0B);
 969                     state = READY;
 970                     break;
 971                 case 0x86:  // Henkan
 972                     matrix_break(0x06);
 973                     state = READY;
 974                     break;
 975                 case 0x87:  // Hiragana
 976                     matrix_break(0x00);
 977                     state = READY;
 978                     break;
 979                 case 0x8B:  // Left GUI
 980                     matrix_break(0x01);
 981                     state = READY;
 982                     break;
 983                 case 0x8C:  // Right GUI
 984                     matrix_break(0x09);
 985                     state = READY;
 986                     break;
 987                 case 0x8D:  // Application
 988                     matrix_break(0x0A);
 989                     state = READY;
 990                     break;
 991                 default:
 992                     state = READY;
 993                     if (code < 0x80) {
 994                         matrix_break(code);
 995                     } else {
 996                         xprintf("!CS3_F0!\n");
 997                         return -1;
 998                     }
 999             }
1000             break;
1001 #ifdef G80_2551_SUPPORT
1002         /*
1003          * G80-2551 terminal keyboard support
1004          * https://deskthority.net/wiki/Cherry_G80-2551
1005          * https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#g80-2551-in-code-set-3
1006          */
1007         case G80:   // G80-2551 four extra keys around cursor keys
1008             switch (code) {
1009                 case (0x26):    // TD= -> JYEN
1010                     matrix_make(0x5D);
1011                     break;
1012                 case (0x25):    // page with edge -> NUHS
1013                     matrix_make(0x53);
1014                     break;
1015                 case (0x16):    // two pages -> RO
1016                     matrix_make(0x51);
1017                     break;
1018                 case (0x1E):    // calc -> KANA
1019                     matrix_make(0x00);
1020                     break;
1021                 case (0xF0):
1022                     state = G80_F0;
1023                     return 0;
1024                 default:
1025                     // Not supported
1026                     matrix_clear();
1027                     break;
1028             }
1029             state = READY;
1030             break;
1031         case G80_F0:
1032             switch (code) {
1033                 case (0x26):    // TD= -> JYEN
1034                     matrix_break(0x5D);
1035                     break;
1036                 case (0x25):    // page with edge -> NUHS
1037                     matrix_break(0x53);
1038                     break;
1039                 case (0x16):    // two pages -> RO
1040                     matrix_break(0x51);
1041                     break;
1042                 case (0x1E):    // calc -> KANA
1043                     matrix_break(0x00);
1044                     break;
1045                 default:
1046                     // Not supported
1047                     matrix_clear();
1048                     break;
1049             }
1050             state = READY;
1051             break;
1052 #endif
1053     }
1054     return 0;
1055 }
1056
1057 /*
1058  * IBM PC Keyboard Protocol Resources:
1059  *
1060  * [a] Microsoft USB HID to PS/2 Translation Table - Scan Code Set 1 and 2
1061  * http://download.microsoft.com/download/1/6/1/161ba512-40e2-4cc9-843a-923143f3456c/translate.pdf
1062  *
1063  * [b] Microsoft Keyboard Scan Code Specification - Special rules of Scan Code Set 1 and 2
1064  * http://download.microsoft.com/download/1/6/1/161ba512-40e2-4cc9-843a-923143f3456c/scancode.doc
1065  *
1066  * [1] PS/2 Reference Manuals - Collection of IBM Personal System/2 documents.
1067  * http://www.mcamafia.de/pdf/pdfref.htm
1068  *
1069  * [2] Keyboard and Auxiliary Device Controller - Signal Timing and Format
1070  * http://www.mcamafia.de/pdf/ibm_hitrc07.pdf
1071  *
1072  * [3] Keyboards(101- and 102-key) - Keyboard Layout, Scan Code Set, POR, and Commands.
1073  * http://www.mcamafia.de/pdf/ibm_hitrc11.pdf
1074  *
1075  * [4] IBM PC XT Keyboard Protocol
1076  * https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-XT-Keyboard-Protocol
1077  *
1078  * [5] IBM Keyboard Scan Code by John Elliott - 83-key, 84-key, 102-key and 122-key
1079  * https://www.seasip.info/VintagePC/index.html
1080  *
1081  * [6] IBM 1391406 Keyboard - Scan Code Set 2 of 102-key PS/2 keyboard
1082  * https://www.seasip.info/VintagePC/ibm_1391406.html
1083  *
1084  * [7] The IBM 6110344 Keyboard - Scan Code Set 3 of 122-key terminal keyboard
1085  * https://www.seasip.info/VintagePC/ibm_6110344.html
1086  *
1087  * [8] IBM PC AT Technical Reference 1986
1088  * http://bitsavers.org/pdf/ibm/pc/at/6183355_PC_AT_Technical_Reference_Mar86.pdf
1089  *
1090  * [y] TrackPoint Engineering Specifications for version 3E
1091  * https://web.archive.org/web/20100526161812/http://wwwcssrv.almaden.ibm.com/trackpoint/download.html
1092  *
1093  * [z] [Soarer's XT/AT/PS2/Terminal to USB converter]
1094  * https://geekhack.org/index.php?topic=17458.0
1095  *
1096  */