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.
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/*
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* Copyright 2002 Red Hat Inc., Durham, North Carolina.
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*
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* All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation on the rights to use, copy, modify, merge,
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* publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the
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* next paragraph) shall be included in all copies or substantial
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* portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NON-INFRINGEMENT. IN NO EVENT SHALL RED HAT AND/OR THEIR SUPPLIERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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* This is a simple test program that reads from /dev/input/event*,
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* decoding events into a human readable form.
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*/
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/*
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* Authors:
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* Rickard E. (Rik) Faith <faith@redhat.com>
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*
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <sys/types.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <time.h>
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#include <linux/input.h>
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struct input_event event;
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int main(int argc, char **argv)
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{
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char name[64]; /* RATS: Use ok, but could be better */
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char buf[256] = { 0, }; /* RATS: Use ok */
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unsigned char mask[EV_MAX/8 + 1]; /* RATS: Use ok */
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int version;
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int fd = 0;
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int rc;
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int i, j;
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char *tmp;
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#define test_bit(bit) (mask[(bit)/8] & (1 << ((bit)%8)))
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for (i = 0; i < 32; i++) {
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sprintf(name, "/dev/input/event%d", i);
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if ((fd = open(name, O_RDONLY, 0)) >= 0) {
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ioctl(fd, EVIOCGVERSION, &version);
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ioctl(fd, EVIOCGNAME(sizeof(buf)), buf);
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ioctl(fd, EVIOCGBIT(0, sizeof(mask)), mask);
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printf("%s\n", name);
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printf(" evdev version: %d.%d.%d\n",
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version >> 16, (version >> 8) & 0xff, version & 0xff);
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printf(" name: %s\n", buf);
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printf(" features:");
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for (j = 0; j < EV_MAX; j++) {
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if (test_bit(j)) {
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const char *type = "unknown";
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switch(j) {
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case EV_KEY: type = "keys/buttons"; break;
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case EV_REL: type = "relative"; break;
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case EV_ABS: type = "absolute"; break;
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case EV_MSC: type = "reserved"; break;
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case EV_LED: type = "leds"; break;
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case EV_SND: type = "sound"; break;
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case EV_REP: type = "repeat"; break;
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case EV_FF: type = "feedback"; break;
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}
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printf(" %s", type);
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}
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}
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printf("\n");
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close(fd);
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}
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}
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if (argc > 1) {
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sprintf(name, "/dev/input/event%d", atoi(argv[1]));
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if ((fd = open(name, O_RDWR, 0)) >= 0) {
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printf("%s: open, fd = %d\n", name, fd);
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for (i = 0; i < LED_MAX; i++) {
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event.time.tv_sec = time(0);
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event.time.tv_usec = 0;
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event.type = EV_LED;
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event.code = i;
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event.value = 0;
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write(fd, &event, sizeof(event));
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}
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while ((rc = read(fd, &event, sizeof(event))) > 0) {
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printf("%-24.24s.%06lu type 0x%04x; code 0x%04x;"
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" value 0x%08x; ",
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ctime(&event.time.tv_sec),
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event.time.tv_usec,
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event.type, event.code, event.value);
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switch (event.type) {
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case EV_KEY:
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if (event.code > BTN_MISC) {
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printf("Button %d %s",
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event.code & 0xff,
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event.value ? "press" : "release");
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} else {
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printf("Key %d (0x%x) %s",
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event.code & 0xff,
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event.code & 0xff,
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event.value ? "press" : "release");
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}
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break;
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case EV_REL:
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switch (event.code) {
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case REL_X: tmp = "X"; break;
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case REL_Y: tmp = "Y"; break;
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case REL_HWHEEL: tmp = "HWHEEL"; break;
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case REL_DIAL: tmp = "DIAL"; break;
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case REL_WHEEL: tmp = "WHEEL"; break;
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case REL_MISC: tmp = "MISC"; break;
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default: tmp = "UNKNOWN"; break;
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}
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printf("Relative %s %d", tmp, event.value);
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break;
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case EV_ABS:
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switch (event.code) {
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case ABS_X: tmp = "X"; break;
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case ABS_Y: tmp = "Y"; break;
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case ABS_Z: tmp = "Z"; break;
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case ABS_RX: tmp = "RX"; break;
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case ABS_RY: tmp = "RY"; break;
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case ABS_RZ: tmp = "RZ"; break;
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case ABS_THROTTLE: tmp = "THROTTLE"; break;
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case ABS_RUDDER: tmp = "RUDDER"; break;
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case ABS_WHEEL: tmp = "WHEEL"; break;
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case ABS_GAS: tmp = "GAS"; break;
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case ABS_BRAKE: tmp = "BRAKE"; break;
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case ABS_HAT0X: tmp = "HAT0X"; break;
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case ABS_HAT0Y: tmp = "HAT0Y"; break;
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case ABS_HAT1X: tmp = "HAT1X"; break;
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case ABS_HAT1Y: tmp = "HAT1Y"; break;
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case ABS_HAT2X: tmp = "HAT2X"; break;
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case ABS_HAT2Y: tmp = "HAT2Y"; break;
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case ABS_HAT3X: tmp = "HAT3X"; break;
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case ABS_HAT3Y: tmp = "HAT3Y"; break;
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case ABS_PRESSURE: tmp = "PRESSURE"; break;
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case ABS_DISTANCE: tmp = "DISTANCE"; break;
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case ABS_TILT_X: tmp = "TILT_X"; break;
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case ABS_TILT_Y: tmp = "TILT_Y"; break;
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case ABS_MISC: tmp = "MISC"; break;
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default: tmp = "UNKNOWN"; break;
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}
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printf("Absolute %s %d", tmp, event.value);
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break;
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case EV_MSC: printf("Misc"); break;
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case EV_LED: printf("Led"); break;
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case EV_SND: printf("Snd"); break;
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case EV_REP: printf("Rep"); break;
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case EV_FF: printf("FF"); break;
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break;
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}
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printf("\n");
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}
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printf("rc = %d, (%s)\n", rc, strerror(errno));
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close(fd);
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}
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}
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return 0;
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}
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