fix 'lf pcf7931 bruteforce' (bug reported in http://www.proxmark.org/forum/viewtopic...

[proxmark3-svn] / client / util.c

diff --git a/client/util.c b/client/util.c
index 32c06e910a31480c2443fb1edfaa70f9b33a35fb..eef97e2abc7d584f0a2b77b7ace367844151a3ff 100644 (file)
--- a/client/util.c
+++ b/client/util.c
@@ -9,12 +9,25 @@
 //-----------------------------------------------------------------------------
 
 #include "util.h"
 //-----------------------------------------------------------------------------
 
 #include "util.h"

+
+#include <stdint.h>
+#include <string.h>
+#include <ctype.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <time.h>
+#include <stdarg.h>
+
+#ifdef _WIN32
+#include <windows.h>
+#endif
+

 #define MAX_BIN_BREAK_LENGTH   (3072+384+1)
 
 #ifndef _WIN32
 #include <termios.h>
 #include <sys/ioctl.h> 
 #define MAX_BIN_BREAK_LENGTH   (3072+384+1)
 
 #ifndef _WIN32
 #include <termios.h>
 #include <sys/ioctl.h> 

-
+#include <unistd.h>

 
 int ukbhit(void)
 {
 
 int ukbhit(void)
 {


@@ -22,25 +35,40 @@ int ukbhit(void)
   int error;
   static struct termios Otty, Ntty;
 
   int error;
   static struct termios Otty, Ntty;
 

-
-  tcgetattr( 0, &Otty);
+  if ( tcgetattr(STDIN_FILENO, &Otty) == -1 ) return -1;

   Ntty = Otty;
 
   Ntty = Otty;
 

-  Ntty.c_iflag          = 0;       /* input mode                */
-  Ntty.c_oflag          = 0;       /* output mode               */
-  Ntty.c_lflag         &= ~ICANON; /* raw mode */
-  Ntty.c_cc[VMIN]       = CMIN;    /* minimum time to wait      */
-  Ntty.c_cc[VTIME]      = CTIME;   /* minimum characters to wait for */
-
-  if (0 == (error = tcsetattr(0, TCSANOW, &Ntty))) {
-    error += ioctl(0, FIONREAD, &cnt);
-    error += tcsetattr(0, TCSANOW, &Otty);
+  Ntty.c_iflag          = 0x0000;   // input mode
+  Ntty.c_oflag          = 0x0000;   // output mode
+  Ntty.c_lflag         &= ~ICANON;  // control mode = raw
+  Ntty.c_cc[VMIN]       = 1;        // return if at least 1 character is in the queue
+  Ntty.c_cc[VTIME]      = 0;               // no timeout. Wait forever
+  
+  if (0 == (error = tcsetattr(STDIN_FILENO, TCSANOW, &Ntty))) {   // set new attributes
+    error += ioctl(STDIN_FILENO, FIONREAD, &cnt);                 // get number of characters availabe
+    error += tcsetattr(STDIN_FILENO, TCSANOW, &Otty);             // reset attributes

   }
 
   return ( error == 0 ? cnt : -1 );
 }
 
   }
 
   return ( error == 0 ? cnt : -1 );
 }
 

-#else
+char getch(void)
+{
+       char c;
+       int error;
+       struct termios Otty, Ntty;
+       if ( tcgetattr(STDIN_FILENO, &Otty) == -1 ) return -1;
+       Ntty = Otty;
+       Ntty.c_lflag &= ~ICANON; /* disable buffered i/o */
+       if (0 == (error = tcsetattr(STDIN_FILENO, TCSANOW, &Ntty))) {   // set new attributes
+               c = getchar();
+               error += tcsetattr(STDIN_FILENO, TCSANOW, &Otty);           // reset attributes
+       }
+       return ( error == 0 ? c : -1 );
+}
+
+#else // _WIN32
+

 #include <conio.h>
 int ukbhit(void) {
        return kbhit();
 #include <conio.h>
 int ukbhit(void) {
        return kbhit();


@@ -94,36 +122,98 @@ void FillFileNameByUID(char *fileName, uint8_t * uid, char *ext, int byteCount)
        memset(fileName, 0x00, 200);
        
        for (int j = 0; j < byteCount; j++, fnameptr += 2)
        memset(fileName, 0x00, 200);
        
        for (int j = 0; j < byteCount; j++, fnameptr += 2)

-               sprintf(fnameptr, "%02x", uid[j]); 
+               sprintf(fnameptr, "%02x", (unsigned int) uid[j]); 

        sprintf(fnameptr, "%s", ext); 
 }
 
        sprintf(fnameptr, "%s", ext); 
 }
 

-// printing and converting functions
+// fill buffer from structure [{uint8_t data, size_t length},...]
+int FillBuffer(uint8_t *data, size_t maxDataLength, size_t *dataLength, ...) {
+       *dataLength = 0;
+       va_list valist;
+       va_start(valist, dataLength);
+       
+       uint8_t *vdata = NULL;
+       size_t vlength = 0;
+       do{
+               vdata = va_arg(valist, uint8_t *);
+               if (!vdata)
+                       break;
+               
+               vlength = va_arg(valist, size_t);
+               if (*dataLength + vlength >  maxDataLength) {
+                       va_end(valist);
+                       return 1;
+               }
+               
+               memcpy(&data[*dataLength], vdata, vlength);
+               *dataLength += vlength;
+               
+       } while (vdata);
+       
+       va_end(valist);

 
 

-void print_hex(const uint8_t * data, const size_t len)
-{
+       return 0;
+}
+
+bool CheckStringIsHEXValue(const char *value) {
+       for (int i = 0; i < strlen(value); i++)
+               if (!isxdigit(value[i]))
+                       return false;
+
+       if (strlen(value) % 2)
+               return false;
+       
+       return true;
+}
+
+void hex_to_buffer(const uint8_t *buf, const uint8_t *hex_data, const size_t hex_len, const size_t hex_max_len, 
+       const size_t min_str_len, const size_t spaces_between, bool uppercase) {
+               
+       char *tmp = (char *)buf;

        size_t i;
        size_t i;

+       memset(tmp, 0x00, hex_max_len);
+
+       int maxLen = ( hex_len > hex_max_len) ? hex_max_len : hex_len;

 
 

-       for (i=0; i < len; i++)
-               printf("%02x ", data[i]);
+       for (i = 0; i < maxLen; ++i, tmp += 2 + spaces_between) {
+               sprintf(tmp, (uppercase) ? "%02X" : "%02x", (unsigned int) hex_data[i]); 
+               
+               for (int j = 0; j < spaces_between; j++)
+                       sprintf(tmp + 2 + j, " ");
+       }
+       
+       i *= (2 + spaces_between);
+       int minStrLen = min_str_len > i ? min_str_len : 0;
+       if (minStrLen > hex_max_len)
+               minStrLen = hex_max_len;
+       for(; i < minStrLen; i++, tmp += 1) 
+               sprintf(tmp, " ");

 
 

-       printf("\n");
+       return;

 }
 
 }
 

+// printing and converting functions
+

 char *sprint_hex(const uint8_t *data, const size_t len) {
 char *sprint_hex(const uint8_t *data, const size_t len) {

+       static char buf[4097] = {0};

        
        

-       int maxLen = ( len > 1024/3) ? 1024/3 : len;
-       static char buf[1024];
-       memset(buf, 0x00, 1024);
-       char *tmp = buf;
-       size_t i;
+       hex_to_buffer((uint8_t *)buf, data, len, sizeof(buf) - 1, 0, 1, false);
+
+       return buf;
+}
+
+char *sprint_hex_inrow_ex(const uint8_t *data, const size_t len, const size_t min_str_len) {
+       static char buf[4097] = {0};

 
 

-       for (i=0; i < maxLen; ++i, tmp += 3)
-               sprintf(tmp, "%02x ", data[i]);
+       hex_to_buffer((uint8_t *)buf, data, len, sizeof(buf) - 1, min_str_len, 0, false);

 
        return buf;
 }
 
 
        return buf;
 }
 

+char *sprint_hex_inrow(const uint8_t *data, const size_t len) {
+       return sprint_hex_inrow_ex(data, len, 0);
+}
+

 char *sprint_bin_break(const uint8_t *data, const size_t len, const uint8_t breaks) {
        // make sure we don't go beyond our char array memory
        int max_len;
 char *sprint_bin_break(const uint8_t *data, const size_t len, const uint8_t breaks) {
        // make sure we don't go beyond our char array memory
        int max_len;


@@ -140,10 +230,11 @@ char *sprint_bin_break(const uint8_t *data, const size_t len, const uint8_t brea
        size_t in_index = 0;
        // loop through the out_index to make sure we don't go too far
        for (size_t out_index=0; out_index < max_len; out_index++) {
        size_t in_index = 0;
        // loop through the out_index to make sure we don't go too far
        for (size_t out_index=0; out_index < max_len; out_index++) {

-               // set character
-               sprintf(tmp++, "%u", data[in_index]);
+               // set character - (should be binary but verify it isn't more than 1 digit)
+               if (data[in_index]<10)
+                       sprintf(tmp++, "%u", (unsigned int) data[in_index]);

                // check if a line break is needed and we have room to print it in our array
                // check if a line break is needed and we have room to print it in our array

-               if ( (breaks > 0) && !((in_index+1) % breaks) && (out_index+1 != max_len) ) {
+               if ( (breaks > 0) && !((in_index+1) % breaks) && (out_index+1 < max_len) ) {

                        // increment and print line break
                        out_index++;
                        sprintf(tmp++, "%s","\n");
                        // increment and print line break
                        out_index++;
                        sprintf(tmp++, "%s","\n");


@@ -157,6 +248,30 @@ char *sprint_bin_break(const uint8_t *data, const size_t len, const uint8_t brea
 char *sprint_bin(const uint8_t *data, const size_t len) {
        return sprint_bin_break(data, len, 0);
 }
 char *sprint_bin(const uint8_t *data, const size_t len) {
        return sprint_bin_break(data, len, 0);
 }

+
+char *sprint_ascii_ex(const uint8_t *data, const size_t len, const size_t min_str_len) {
+       static char buf[1024];
+       char *tmp = buf;
+       memset(buf, 0x00, 1024);
+       size_t max_len = (len > 1010) ? 1010 : len;
+       size_t i = 0;
+       while(i < max_len){
+               char c = data[i];
+               tmp[i] = ((c < 32) || (c == 127)) ? '.' : c;
+               ++i;
+       }
+       
+       int minStrLen = min_str_len > i ? min_str_len : 0;
+       for(; i < minStrLen; ++i) 
+               tmp[i] = ' ';
+       
+       return buf;
+}
+
+char *sprint_ascii(const uint8_t *data, const size_t len) {
+    return sprint_ascii_ex(data, len, 0);
+}
+

 void num_to_bytes(uint64_t n, size_t len, uint8_t* dest)
 {
        while (len--) {
 void num_to_bytes(uint64_t n, size_t len, uint8_t* dest)
 {
        while (len--) {


@@ -183,6 +298,24 @@ void num_to_bytebits(uint64_t      n, size_t len, uint8_t *dest) {
        }
 }
 
        }
 }
 

+//least significant bit first
+void num_to_bytebitsLSBF(uint64_t n, size_t len, uint8_t *dest) {
+       for(int i = 0 ; i < len ; ++i) {
+               dest[i] =  n & 1;
+               n >>= 1;
+       }
+}
+
+// Swap bit order on a uint32_t value.  Can be limited by nrbits just use say 8bits reversal
+// And clears the rest of the bits.
+uint32_t SwapBits(uint32_t value, int nrbits) {
+       uint32_t newvalue = 0;
+       for(int i = 0; i < nrbits; i++) {
+               newvalue ^= ((value >> i) & 1) << (nrbits - 1 - i);
+       }
+       return newvalue;
+}
+

 // aa,bb,cc,dd,ee,ff,gg,hh, ii,jj,kk,ll,mm,nn,oo,pp
 // to
 // hh,gg,ff,ee,dd,cc,bb,aa, pp,oo,nn,mm,ll,kk,jj,ii
 // aa,bb,cc,dd,ee,ff,gg,hh, ii,jj,kk,ll,mm,nn,oo,pp
 // to
 // hh,gg,ff,ee,dd,cc,bb,aa, pp,oo,nn,mm,ll,kk,jj,ii


@@ -200,7 +333,7 @@ uint8_t *SwapEndian64(const uint8_t *src, const size_t len, const uint8_t blockS
 }
 
 //assumes little endian
 }
 
 //assumes little endian

-char * printBits(size_t const size, void const * const ptr)
+char *printBits(size_t const size, void const * const ptr)

 {
     unsigned char *b = (unsigned char*) ptr;   
     unsigned char byte;
 {
     unsigned char *b = (unsigned char*) ptr;   
     unsigned char byte;


@@ -214,20 +347,37 @@ char * printBits(size_t const size, void const * const ptr)
         {
             byte = b[i] & (1<<j);
             byte >>= j;
         {
             byte = b[i] & (1<<j);
             byte >>= j;

-            sprintf(tmp, "%u", byte);
+            sprintf(tmp, "%u", (unsigned int)byte);

                        tmp++;
         }
     }
        return buf;
 }
 
                        tmp++;
         }
     }
        return buf;
 }
 

+char * printBitsPar(const uint8_t *b, size_t len) {
+       static char buf1[512] = {0};
+       static char buf2[512] = {0};
+       static char *buf;
+       if (buf != buf1)
+               buf = buf1;
+       else
+               buf = buf2;
+       memset(buf, 0x00, 512);
+
+       for (int i = 0; i < len; i++) {
+               buf[i] = ((b[i / 8] << (i % 8)) & 0x80) ? '1':'0';
+       }
+       return buf;
+}
+
+

 //  -------------------------------------------------------------------------
 //  string parameters lib
 //  -------------------------------------------------------------------------
 
 //  -------------------------------------------------------------------------
 //  line     - param line
 //  -------------------------------------------------------------------------
 //  string parameters lib
 //  -------------------------------------------------------------------------
 
 //  -------------------------------------------------------------------------
 //  line     - param line

-//  bg, en   - symbol numbers in param line of beginning an ending parameter
+//  bg, en   - symbol numbers in param line of beginning and ending parameter

 //  paramnum - param number (from 0)
 //  -------------------------------------------------------------------------
 int param_getptr(const char *line, int *bg, int *en, int paramnum)
 //  paramnum - param number (from 0)
 //  -------------------------------------------------------------------------
 int param_getptr(const char *line, int *bg, int *en, int paramnum)


@@ -260,13 +410,28 @@ int param_getptr(const char *line, int *bg, int *en, int paramnum)
 }
 
 
 }
 
 

-char param_getchar(const char *line, int paramnum)
+int param_getlength(const char *line, int paramnum)

 {
        int bg, en;
        
 {
        int bg, en;
        

+       if (param_getptr(line, &bg, &en, paramnum)) return 0;
+
+       return en - bg + 1;
+}
+
+char param_getchar(const char *line, int paramnum) {
+       return param_getchar_indx(line, 0, paramnum);
+}
+
+char param_getchar_indx(const char *line, int indx, int paramnum) {
+       int bg, en;
+       

        if (param_getptr(line, &bg, &en, paramnum)) return 0x00;
 
        if (param_getptr(line, &bg, &en, paramnum)) return 0x00;
 

-       return line[bg];
+       if (bg + indx > en)
+               return '\0';
+       
+       return line[bg + indx];

 }
 
 uint8_t param_get8(const char *line, int paramnum)
 }
 
 uint8_t param_get8(const char *line, int paramnum)


@@ -331,8 +496,6 @@ uint64_t param_get64ex(const char *line, int paramnum, int deflt, int base)
                return strtoull(&line[bg], NULL, base);
        else
                return deflt;
                return strtoull(&line[bg], NULL, base);
        else
                return deflt;

-
-       return 0;

 }
 
 int param_gethex(const char *line, int paramnum, uint8_t * data, int hexcnt)
 }
 
 int param_gethex(const char *line, int paramnum, uint8_t * data, int hexcnt)


@@ -348,7 +511,7 @@ int param_gethex(const char *line, int paramnum, uint8_t * data, int hexcnt)
                return 1;
 
        for(i = 0; i < hexcnt; i += 2) {
                return 1;
 
        for(i = 0; i < hexcnt; i += 2) {

-               if (!(isxdigit(line[bg + i]) && isxdigit(line[bg + i + 1])) )   return 1;
+               if (!(isxdigit((unsigned char)line[bg + i]) && isxdigit((unsigned char)line[bg + i + 1])) )     return 1;

                
                sscanf((char[]){line[bg + i], line[bg + i + 1], 0}, "%X", &temp);
                data[i / 2] = temp & 0xff;
                
                sscanf((char[]){line[bg + i], line[bg + i + 1], 0}, "%X", &temp);
                data[i / 2] = temp & 0xff;


@@ -370,7 +533,7 @@ int param_gethex_ex(const char *line, int paramnum, uint8_t * data, int *hexcnt)
                return 1;
 
        for(i = 0; i < *hexcnt; i += 2) {
                return 1;
 
        for(i = 0; i < *hexcnt; i += 2) {

-               if (!(isxdigit(line[bg + i]) && isxdigit(line[bg + i + 1])) )   return 1;
+               if (!(isxdigit((unsigned char)line[bg + i]) && isxdigit((unsigned char)line[bg + i + 1])) )     return 1;

                
                sscanf((char[]){line[bg + i], line[bg + i + 1], 0}, "%X", &temp);
                data[i / 2] = temp & 0xff;
                
                sscanf((char[]){line[bg + i], line[bg + i + 1], 0}, "%X", &temp);
                data[i / 2] = temp & 0xff;


@@ -378,11 +541,66 @@ int param_gethex_ex(const char *line, int paramnum, uint8_t * data, int *hexcnt)
 
        return 0;
 }
 
        return 0;
 }

-int param_getstr(const char *line, int paramnum, char * str)
+
+int param_gethex_to_eol(const char *line, int paramnum, uint8_t * data, int maxdatalen, int *datalen) {
+       int bg, en;
+       uint32_t temp;
+       char buf[5] = {0};
+
+       if (param_getptr(line, &bg, &en, paramnum)) return 1;
+
+       *datalen = 0;
+       
+       int indx = bg;
+       while (line[indx]) {
+               if (line[indx] == '\t' || line[indx] == ' ') {
+                       indx++;
+                       continue;
+               }
+               
+               if (isxdigit((unsigned char)line[indx])) {
+                       buf[strlen(buf) + 1] = 0x00;
+                       buf[strlen(buf)] = line[indx];
+               } else {
+                       // if we have symbols other than spaces and hex
+                       return 1;
+               }                               
+
+               if (*datalen >= maxdatalen) {
+                       // if we dont have space in buffer and have symbols to translate
+                       return 2;
+               }
+
+               if (strlen(buf) >= 2) {
+                       sscanf(buf, "%x", &temp);
+                       data[*datalen] = (uint8_t)(temp & 0xff);
+                       *buf = 0;
+                       (*datalen)++;
+               }
+               
+               indx++;
+       }
+
+       if (strlen(buf) > 0) 
+               //error when not completed hex bytes
+               return 3;
+               
+       return 0;
+}
+
+int param_getstr(const char *line, int paramnum, char * str, size_t buffersize)

 {
        int bg, en;
 
 {
        int bg, en;
 

-       if (param_getptr(line, &bg, &en, paramnum)) return 0;
+       if (param_getptr(line, &bg, &en, paramnum)) {   
+               return 0;
+       }
+
+       // Prevent out of bounds errors
+       if (en - bg + 1 >= buffersize) {
+               printf("out of bounds error: want %d bytes have %zd bytes\n", en - bg + 1 + 1, buffersize);
+               return 0;
+       }

        
        memcpy(str, line + bg, en - bg + 1);
        str[en - bg + 1] = 0;
        
        memcpy(str, line + bg, en - bg + 1);
        str[en - bg + 1] = 0;


@@ -400,6 +618,7 @@ https://github.com/ApertureLabsLtd/RFIDler/blob/master/firmware/Pic32/RFIDler.X/
 int hextobinarray(char *target, char *source)
 {
     int length, i, count= 0;
 int hextobinarray(char *target, char *source)
 {
     int length, i, count= 0;

+    char* start = source;

     char x;
 
     length = strlen(source);
     char x;
 
     length = strlen(source);


@@ -415,8 +634,10 @@ int hextobinarray(char *target, char *source)
             x -= '0';
         else if (x >= 'A' && x <= 'F')
             x -= 'A' - 10;
             x -= '0';
         else if (x >= 'A' && x <= 'F')
             x -= 'A' - 10;

-        else
+        else {
+               printf("Discovered unknown character %c %d at idx %tu of %s\n", x, x, source - start, start);

             return 0;
             return 0;

+        }

         // output
         for(i= 0 ; i < 4 ; ++i, ++count)
             *(target++)= (x >> (3 - i)) & 1;
         // output
         for(i= 0 ; i < 4 ; ++i, ++count)
             *(target++)= (x >> (3 - i)) & 1;


@@ -425,17 +646,6 @@ int hextobinarray(char *target, char *source)
     return count;
 }
 
     return count;
 }
 

-// convert hex to human readable binary string
-int hextobinstring(char *target, char *source)
-{
-    int length;
-
-    if(!(length= hextobinarray(target, source)))
-        return 0;
-    binarraytobinstring(target, target, length);
-    return length;
-}
-

 // convert binary array of 0x00/0x01 values to hex (safe to do in place as target will always be shorter than source)
 // return number of bits converted
 int binarraytohex(char *target,char *source, int length)
 // convert binary array of 0x00/0x01 values to hex (safe to do in place as target will always be shorter than source)
 // return number of bits converted
 int binarraytohex(char *target,char *source, int length)


@@ -450,7 +660,7 @@ int binarraytohex(char *target,char *source, int length)
     {
         for(i= x= 0 ; i < 4 ; ++i)
             x +=  ( source[i] << (3 - i));
     {
         for(i= x= 0 ; i < 4 ; ++i)
             x +=  ( source[i] << (3 - i));

-        sprintf(target,"%X", x);
+        sprintf(target,"%X", (unsigned int)x);

         ++target;
         source += 4;
         j -= 4;
         ++target;
         source += 4;
         j -= 4;


@@ -458,16 +668,6 @@ int binarraytohex(char *target,char *source, int length)
     return length;
 }
 
     return length;
 }
 

-// convert binary array to human readable binary
-void binarraytobinstring(char *target, char *source,  int length)
-{
-    int i;
-
-    for(i= 0 ; i < length ; ++i)
-        *(target++)= *(source++) + '0';
-    *target= '\0';
-}
-

 // return parity bit required to match type
 uint8_t GetParity( uint8_t *bits, uint8_t type, int length)
 {
 // return parity bit required to match type
 uint8_t GetParity( uint8_t *bits, uint8_t type, int length)
 {


@@ -489,11 +689,68 @@ void wiegand_add_parity(uint8_t *target, uint8_t *source, uint8_t length)
     *(target)= GetParity(source + length / 2, ODD, length / 2);
 }
 
     *(target)= GetParity(source + length / 2, ODD, length / 2);
 }
 

+// xor two arrays together for len items.  The dst array contains the new xored values.

 void xor(unsigned char *dst, unsigned char *src, size_t len) {
    for( ; len > 0; len--,dst++,src++)
        *dst ^= *src;
 }
 
 void xor(unsigned char *dst, unsigned char *src, size_t len) {
    for( ; len > 0; len--,dst++,src++)
        *dst ^= *src;
 }
 

-int32_t le24toh (uint8_t data[3]) {
-    return (data[2] << 16) | (data[1] << 8) | data[0];
+// RotateLeft - Ultralight, Desfire, works on byte level
+// 00-01-02  >> 01-02-00
+void rol(uint8_t *data, const size_t len){
+    uint8_t first = data[0];
+    for (size_t i = 0; i < len-1; i++) {
+        data[i] = data[i+1];
+    }
+    data[len-1] = first;
+}
+
+
+// Replace unprintable characters with a dot in char buffer
+void clean_ascii(unsigned char *buf, size_t len) {
+  for (size_t i = 0; i < len; i++) {
+    if (!isprint(buf[i]))
+      buf[i] = '.';
+  }

 }
 }

+
+// replace \r \n to \0
+void strcleanrn(char *buf, size_t len) {
+       strcreplace(buf, len, '\n', '\0');
+       strcreplace(buf, len, '\r', '\0');
+}
+
+// replace char in buffer
+void strcreplace(char *buf, size_t len, char from, char to) {
+  for (size_t i = 0; i < len; i++) {
+    if (buf[i] == from)
+      buf[i] = to;
+  }
+}
+
+char *strmcopy(char *buf) {
+       char * str = NULL;
+       if ((str = (char*) malloc(strlen(buf) + 1)) != NULL) {
+               memset(str, 0, strlen(buf) + 1);
+               strcpy(str, buf);
+       }       
+       return str;
+}
+
+
+// determine number of logical CPU cores (use for multithreaded functions)
+extern int num_CPUs(void)
+{
+#if defined(_WIN32)
+       #include <sysinfoapi.h>
+       SYSTEM_INFO sysinfo;
+       GetSystemInfo(&sysinfo);
+       return sysinfo.dwNumberOfProcessors;
+#elif defined(__linux__) || defined(__APPLE__)
+       #include <unistd.h>
+       return sysconf(_SC_NPROCESSORS_ONLN);
+#else
+       return 1;
+#endif
+}
+