#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <limits.h>

#include "card.h"

/* Read a 16-bit unsigned int from a pci id file */
unsigned short read_pci_id(char *device_path, char *field)
{
	char buf[16];
	char file_path[PATH_MAX];
	
	strcpy(file_path, device_path);
	strcat(file_path, field);
	
	FILE *fp = fopen(file_path, "r");
	
	if (fp == NULL)
		return 0;
		
	if (fgets(buf, sizeof(buf), fp) == NULL) {
		fclose(fp);
		return 0;
	}
	
	fclose(fp);
	
	return (unsigned short)strtoul(buf, NULL, 16);
}

char *read_nvidia_pci_address(char *device_path)
{
	char file_path[PATH_MAX];
	
	char *ret = calloc(16 + 1, sizeof(char)); /* assuming pci ids could look as large as 00000000:0C:00.0 */
	
	strcpy(file_path, device_path);
	strcat(file_path, "/name");
	
	FILE *fp = fopen(file_path, "r");
	
	if (fp == NULL) {
		free(ret);
		return NULL;
	}
	
	fscanf(fp, "NVIDIA i2c adapter %*u at %16s", ret);
	fclose(fp);
	
	if (strlen(ret) == 0) {
		free(ret);
		return NULL;
	}
	
	return ret;
}