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질문 제목 : 이렇개 작성된 씨 언어 인대

각각의 주석을 달려고 하는대 어렵내요 도와주세요 (주석달기)주석좀 달아주세요~~~~질문 내용 :

#include stdio.h
#include string.h
#include stdlib.h
#include unistd.h
#include sys/mman.h
#include fcntl.h
#define fpga_baseaddress 0x88000000
//#define buzzer_offset 0x50 // buzzer register
#define key_col_offset 0x70 // keypad column register
#define key_row_offset 0x72 // keypad row register
int main(void)
{
short value;
unsigned short *addr_fpga;
unsigned short *keypad_row_addr, *keypad_col_addr, *buzzer_addr;

int fd;
int i,quit=1;
if ((fd=open(/dev/mem,o_rdwr|o_sync)) 0) {
perror(mem open fail\n);
exit(1);
}

addr_fpga= (unsigned short *)mmap(null, 4096, prot_write|prot_read, map_shared, fd, fpga_baseaddress);
keypad_col_addr = addr_fpga + key_col_offset/sizeof(unsigned short);
keypad_row_addr = addr_fpga + key_row_offset/sizeof(unsigned short);
//buzzer_addr = addr_fpga + buzzer_offset/sizeof(unsigned short);

if(*keypad_row_addr ==(unsigned short)-1 || *keypad_col_addr
==(unsigned short)-1 ) {
close(fd);
printf(mmap error\n);
exit(1);
}
printf(- keypad\n);
printf(press the key button!\n);
printf(press the key 0x16 to exit!\n);

while(1)
{
*keypad_row_addr = 0x01;
usleep(1000);
value =(*keypad_col_addr & 0x0f);
*keypad_row_addr = 0x00;
switch(value) {
case 0x01 : value = 0x01; break;
case 0x02 : value = 0x02; break;
case 0x04 : value = 0x03; break;
case 0x08 : value = 0x04; break;
}
if(value != 0x00) goto stop_poll;
*keypad_row_addr = 0x02;
for(i=0;i2000;i++);
value = value|(*keypad_col_addr & 0x0f);
*keypad_row_addr = 0x00;
switch(value) {
case 0x01 : value = 0x05; break;
case 0x02 : value = 0x06; break;
case 0x04 : value = 0x07; break;
case 0x08 : value = 0x08; break;
}
if(value != 0x00) goto stop_poll;
*keypad_row_addr = 0x04;
for(i=0;i2000;i++);
value = value|(*keypad_col_addr & 0x0f);
*keypad_row_addr = 0x00;
switch(value) {
case 0x01 : value = 0x09; break;
case 0x02 : value = 0x0a; break;
case 0x04 : value = 0x0b; break;
case 0x08 : value = 0x0c; break;
}
if(value != 0x00) goto stop_poll;
*keypad_row_addr = 0x08;
for(i=0;i2000;i++);
value = value|(*keypad_col_addr & 0x0f);
*keypad_row_addr = 0x00;
switch(value) {
case 0x01 : value = 0x0d; break;
case 0x02 : value = 0x0e; break;
case 0x04 : value = 0x0f; break;
case 0x08 : value = 0x10; break;
}
stop_poll:
if(value0) {
printf(\n pressed key = %x\n,value-1);
//*buzzer_addr=0x1;
usleep(50000);
//*buzzer_addr=0x0;
}
else *keypad_row_addr = 0x00;
for(i=0;i4000000;i++);
if(value == 16) {

//*buzzer_addr=0x1;
usleep(150000);
//*buzzer_addr=0x0;
quit = 0;
}
}
munmap(addr_fpga,4096);
close(fd);
return 0;
}

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