add log10() function

src/calc.c

@@ -118,12 +118,21 @@ void process_cmd(char cmd){
 			toggle_shifted();
 		} break;
 		//////////
+		case '9':{
+			if (IsShifted && !decn_is_nan(&stack(STACK_X))){ //log10(x)
+				copy_decn(&AccDecn, &stack(STACK_X));
+				log10_decn();
+				copy_decn(&stack(STACK_X), &AccDecn);
+				IsShifted = 0;
+			}
+		} break;
+		//////////
 		case '8':{
 			if (IsShifted && !decn_is_nan(&stack(STACK_X))){ //ln(x)
 				copy_decn(&AccDecn, &stack(STACK_X));
 				ln_decn();
 				copy_decn(&stack(STACK_X), &AccDecn);
-				toggle_shifted();
+				IsShifted = 0;
 			}
 		} break;
 		//////////

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 Tmp2Decn; //used by div_decn() and ln_decn()
-__idata dec80 Tmp3Decn; //used by div_decn()
+__idata dec80 Tmp3Decn; //used by div_decn() and ln_decn()
-__idata dec80 Tmp4Decn; //used by div_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