add log10() function

src/decn/decn.c

@@ -47,9 +47,9 @@ static const uint8_t num_digits_display = 16;
 
 __idata dec80 AccDecn, BDecn;
 __idata dec80 TmpDecn; //used by add_decn() and mult_decn()
-__idata dec80 Tmp2Decn; //used by div_decn()
-__idata dec80 Tmp3Decn; //used by div_decn()
-__idata dec80 Tmp4Decn; //used by div_decn()
+__idata dec80 Tmp2Decn; //used by div_decn() and ln_decn()
+__idata dec80 Tmp3Decn; //used by div_decn() and ln_decn()
+__idata dec80 Tmp4Decn; //used by div_decn() and ln_decn()
 
 __xdata char Buf[DECN_BUF_SIZE];
 
@@ -1015,6 +1015,12 @@ void ln_decn(void){
 #undef NUM_A_ARR
 }
 
+void log10_decn(void){
+	ln_decn();
+	copy_decn(&BDecn, &DECN_LN_10);
+	div_decn();
+}
+
 static void set_str_error(void){
 	Buf[0] = 'E';
 	Buf[1] = 'r';

src/decn/decn.h

@@ -69,6 +69,7 @@ void mult_decn(void);
 void div_decn(void);
 
 void ln_decn(void);
+void log10_decn(void);
 
 //Buf should hold at least 18 + 4 + 5 + 1 = 28
 #define DECN_BUF_SIZE 28