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如何读取Linux键值，输入子系统，key，dev/input/event，dev/event，C语言键盘

分类： 嵌入式

2015-06-10 17:52:58

http://blog.csdn.net/lanmanck/article/details/8423669

相信各位使用嵌入式的都希望直接读取键值，特别是芯片厂家已经提供input驱动的情况下，例如GPIO或者扫描类型的键盘。那么在应用层如何通过C语言获取键值呢？

给兄弟们一个重量级的源码，看下面，大家拿去编译运行就知道怎么回事了，当然，可以使用select而不是while()来读取更好一点，留给各位去想象了：

注意：

#include

为内核源码的头文件，注意路径，一般为kernel/include/linux/input.

点击(此处)折叠或打开

  1. /*
  2.  * Copyright 2002 Red Hat Inc., Durham, North Carolina.
  3.  *
  4.  * All Rights Reserved.
  5.  *
  6.  * Permission is hereby granted, free of charge, to any person obtaining
  7.  * a copy of this software and associated documentation files (the
  8.  * "Software"), to deal in the Software without restriction, including
  9.  * without limitation on the rights to use, copy, modify, merge,
  10.  * publish, distribute, sublicense, and/or sell copies of the Software,
  11.  * and to permit persons to whom the Software is furnished to do so,
  12.  * subject to the following conditions:
  13.  *
  14.  * The above copyright notice and this permission notice (including the
  15.  * next paragraph) shall be included in all copies or substantial
  16.  * portions of the Software.
  17.  *
  18.  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  19.  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  20.  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  21.  * NON-INFRINGEMENT. IN NO EVENT SHALL RED HAT AND/OR THEIR SUPPLIERS
  22.  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  23.  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  24.  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  25.  * SOFTWARE.
  26.  *
  27.  * This is a simple test program that reads from /dev/input/event*,
  28.  * decoding events into a human readable form.
  29.  */
  30.   
  31. /*
  32.  * Authors:
  33.  * Rickard E. (Rik) Faith <faith@redhat.com>
  34.  *
  35.  */
  36.   
  37. #include <stdio.h>
  38. #include <stdlib.h>
  39. #include <unistd.h>
  40. #include <string.h>
  41. #include <sys/types.h>
  42. #include <fcntl.h>
  43. #include <errno.h>
  44. #include <time.h>
  45. #include <linux/input.h>
  46.   
  47. struct input_event event;
  48.   
  49. int main(int argc, char **argv)
  50. {
  51.     char name[64]; /* RATS: Use ok, but could be better */
  52.     char buf[256] = { 0, }; /* RATS: Use ok */
  53.     unsigned char mask[EV_MAX/8 + 1]; /* RATS: Use ok */
  54.     int version;
  55.     int fd = 0;
  56.     int rc;
  57.     int i, j;
  58.     char *tmp;
  59.   
  60. #define test_bit(bit) (mask[(bit)/8] & (1 << ((bit)%8)))
  61.   
  62.     for (i = 0; i < 32; i++) {
  63.         sprintf(name, "/dev/input/event%d", i);
  64.         if ((fd = open(name, O_RDONLY, 0)) >= 0) {
  65.             ioctl(fd, EVIOCGVERSION, &version);
  66.             ioctl(fd, EVIOCGNAME(sizeof(buf)), buf);
  67.             ioctl(fd, EVIOCGBIT(0, sizeof(mask)), mask);
  68.             printf("%s\n", name);
  69.             printf(" evdev version: %d.%d.%d\n",
  70.                    version >> 16, (version >> 8) & 0xff, version & 0xff);
  71.             printf(" name: %s\n", buf);
  72.             printf(" features:");
  73.             for (j = 0; j < EV_MAX; j++) {
  74.                 if (test_bit(j)) {
  75.                     const char *type = "unknown";
  76.                     switch(j) {
  77.                     case EV_KEY: type = "keys/buttons"; break;
  78.                     case EV_REL: type = "relative"; break;
  79.                     case EV_ABS: type = "absolute"; break;
  80.                     case EV_MSC: type = "reserved"; break;
  81.                     case EV_LED: type = "leds"; break;
  82.                     case EV_SND: type = "sound"; break;
  83.                     case EV_REP: type = "repeat"; break;
  84.                     case EV_FF: type = "feedback"; break;
  85.                     }
  86.                     printf(" %s", type);
  87.                 }
  88.             }
  89.             printf("\n");
  90.             close(fd);
  91.         }
  92.     }
  93.   
  94.     if (argc > 1) {
  95.         sprintf(name, "/dev/input/event%d", atoi(argv[1]));
  96.         if ((fd = open(name, O_RDWR, 0)) >= 0) {
  97.             printf("%s: open, fd = %d\n", name, fd);
  98.             for (i = 0; i < LED_MAX; i++) {
  99.                 event.time.tv_sec = time(0);
  100.                 event.time.tv_usec = 0;
  101.                 event.type = EV_LED;
  102.                 event.code = i;
  103.                 event.value = 0;
  104.                 write(fd, &event, sizeof(event));
  105.             }
  106.               
  107.             while ((rc = read(fd, &event, sizeof(event))) > 0) {
  108.                 printf("%-24.24s.%06lu type 0x%04x; code 0x%04x;"
  109.                        " value 0x%08x; ",
  110.                        ctime(&event.time.tv_sec),
  111.                        event.time.tv_usec,
  112.                        event.type, event.code, event.value);
  113.                 switch (event.type) {
  114.                 case EV_KEY:
  115.                     if (event.code > BTN_MISC) {
  116.                         printf("Button %d %s",
  117.                                event.code & 0xff,
  118.                                event.value ? "press" : "release");
  119.                     } else {
  120.                         printf("Key %d (0x%x) %s",
  121.                                event.code & 0xff,
  122.                                event.code & 0xff,
  123.                                event.value ? "press" : "release");
  124.                     }
  125.                     break;
  126.                 case EV_REL:
  127.                     switch (event.code) {
  128.                     case REL_X: tmp = "X"; break;
  129.                     case REL_Y: tmp = "Y"; break;
  130.                     case REL_HWHEEL: tmp = "HWHEEL"; break;
  131.                     case REL_DIAL: tmp = "DIAL"; break;
  132.                     case REL_WHEEL: tmp = "WHEEL"; break;
  133.                     case REL_MISC: tmp = "MISC"; break;
  134.                     default: tmp = "UNKNOWN"; break;
  135.                     }
  136.                     printf("Relative %s %d", tmp, event.value);
  137.                     break;
  138.                 case EV_ABS:
  139.                     switch (event.code) {
  140.                     case ABS_X: tmp = "X"; break;
  141.                     case ABS_Y: tmp = "Y"; break;
  142.                     case ABS_Z: tmp = "Z"; break;
  143.                     case ABS_RX: tmp = "RX"; break;
  144.                     case ABS_RY: tmp = "RY"; break;
  145.                     case ABS_RZ: tmp = "RZ"; break;
  146.                     case ABS_THROTTLE: tmp = "THROTTLE"; break;
  147.                     case ABS_RUDDER: tmp = "RUDDER"; break;
  148.                     case ABS_WHEEL: tmp = "WHEEL"; break;
  149.                     case ABS_GAS: tmp = "GAS"; break;
  150.                     case ABS_BRAKE: tmp = "BRAKE"; break;
  151.                     case ABS_HAT0X: tmp = "HAT0X"; break;
  152.                     case ABS_HAT0Y: tmp = "HAT0Y"; break;
  153.                     case ABS_HAT1X: tmp = "HAT1X"; break;
  154.                     case ABS_HAT1Y: tmp = "HAT1Y"; break;
  155.                     case ABS_HAT2X: tmp = "HAT2X"; break;
  156.                     case ABS_HAT2Y: tmp = "HAT2Y"; break;
  157.                     case ABS_HAT3X: tmp = "HAT3X"; break;
  158.                     case ABS_HAT3Y: tmp = "HAT3Y"; break;
  159.                     case ABS_PRESSURE: tmp = "PRESSURE"; break;
  160.                     case ABS_DISTANCE: tmp = "DISTANCE"; break;
  161.                     case ABS_TILT_X: tmp = "TILT_X"; break;
  162.                     case ABS_TILT_Y: tmp = "TILT_Y"; break;
  163.                     case ABS_MISC: tmp = "MISC"; break;
  164.                     default: tmp = "UNKNOWN"; break;
  165.                     }
  166.                     printf("Absolute %s %d", tmp, event.value);
  167.                     break;
  168.                 case EV_MSC: printf("Misc"); break;
  169.                 case EV_LED: printf("Led"); break;
  170.                 case EV_SND: printf("Snd"); break;
  171.                 case EV_REP: printf("Rep"); break;
  172.                 case EV_FF: printf("FF"); break;
  173.                     break;
  174.                 }
  175.                 printf("\n");
  176.             }
  177.             printf("rc = %d, (%s)\n", rc, strerror(errno));
  178.             close(fd);
  179.         }
  180.     }
  181.     return 0;
  182. }

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