#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include "hwlib.h"
#include "socal/socal.h"
#include "socal/hps.h"
#include "socal/alt_gpio.h"
#include "hps_0.h"
#define HW_REGS_BASE ( ALT_STM_OFST )
#define HW_REGS_SPAN ( 0x04000000 )
#define HW_REGS_MASK ( HW_REGS_SPAN - 1 )
int main() {
void *virtual_base;
int fd;
int loop_count;
int led_direction;
int led_mask;
void *h2p_lw_led_addr;
// map the address space for the LED registers into user space so we can interact with them.
// we'll actually map in the entire CSR span of the HPS since we want to access various registers within that span
if( ( fd = open( "/dev/mem", ( O_RDWR | O_SYNC ) ) ) == -1 ) {
printf( "ERROR: could not open \"/dev/mem\"...\n" );
return( 1 );
}
virtual_base = mmap( NULL, HW_REGS_SPAN, ( PROT_READ | PROT_WRITE ), MAP_SHARED, fd, HW_REGS_BASE );
if( virtual_base == MAP_FAILED ) {
printf( "ERROR: mmap() failed...\n" );
close( fd );
return( 1 );
}
h2p_lw_led_addr=virtual_base + ( ( unsigned long )( ALT_LWFPGASLVS_OFST + PIO_LED_BASE ) & ( unsigned long)( HW_REGS_MASK ) );
// toggle the LEDs a bit
loop_count = 0;
led_mask = 0x01;
led_direction = 0; // 0: left to right direction
while( loop_count < 60 ) {
// control led, add ~ because the led is low-active
*(uint32_t *)h2p_lw_led_addr = ~led_mask;
// wait 100ms
usleep( 100*1000 );
// update led mask
if (led_direction == 0){
led_mask <<= 1;
if (led_mask == (0x01 << (PIO_LED_DATA_WIDTH-1)))
led_direction = 1;
}else{
led_mask >>= 1;
if (led_mask == 0x01){
led_direction = 0;
loop_count++;
}
}
} // while
// clean up our memory mapping and exit
if( munmap( virtual_base, HW_REGS_SPAN ) != 0 ) {
printf( "ERROR: munmap() failed...\n" );
close( fd );
return( 1 );
}
close( fd );
return( 0 );
}
首先说h2p_lw_led_addr=virtual_base + ( ( unsigned long )( ALT_LWFPGASLVS_OFST + PIO_LED_BASE ) & ( unsigned long)( HW_REGS_MASK ) );，ALT_LWFPGASLVS_OFST 是什么？ 我发现他的值是0xff200000，在<hps.h>头文件里。在qsys工程里面有一个Pio_led的元件，他相对于lwaxi的偏移地址被宏定义为PIO_LED_BASE，其值为0x0，( unsigned long )( ALT_LWFPGASLVS_OFST + PIO_LED_BASE，这两个加起来是什么意思，为什么要加起来？然后为什么又与 HW_REGS_MASK进行一个与?最开始的几个宏定义的值代表着什么意思？ 在其中一个宏定义里面有用到ALT_STM_OFST，这个是什么？
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