add LST

G4:G431/CORDIC/strfunc.c

@@ -15,6 +15,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <math.h> // isnan/isinf
 #include <stm32g4.h>
 #include <string.h>
 
@@ -262,3 +263,116 @@ char *getint(char *txt, int32_t *I){
     *I = sign * (int32_t)U;
     return nxt;
 }
+
+// be careful: if pow10 would be bigger you should change str[] size!
+static const float pwr10[] = {1.f,   10.f,  100.f,  1000.f,  10000.f,  100000.f,  1000000.f,  10000000.f};
+static const float rounds[] = {0.5f, 0.05f, 0.005f, 0.0005f, 0.00005f, 0.000005f, 0.0000005f, 0.00000005f};
+#define P10L  (sizeof(pwr10)/sizeof(float) - 1)
+char *float2str(float x, uint8_t prec){
+    static char str[16] = {0}; // -117.5494E-36\0 - 14 symbols max!
+    if(prec > P10L) prec = P10L;
+    if(isnan(x)){ memcpy(str, "NAN", 4); return str;}
+    else{
+        int i = isinf(x);
+        if(i){memcpy(str, "-INF", 5); if(i == 1) return str+1; else return str;}
+    }
+    char *s = str + 14; // go to end of buffer
+    uint8_t minus = 0;
+    if(x < 0){
+        x = -x;
+        minus = 1;
+    }
+    int pow = 0; // xxxEpow
+    // now convert float to 1.xxxE3y
+    while(x > 1000.f){
+        x /= 1000.f;
+        pow += 3;
+    }
+    if(x > 0.) while(x < 1.){
+            x *= 1000.f;
+            pow -= 3;
+        }
+    // print Eyy
+    if(pow){
+        uint8_t m = 0;
+        if(pow < 0){pow = -pow; m = 1;}
+        while(pow){
+            int p10 = pow/10;
+            *s-- = '0' + (pow - 10*p10);
+            pow = p10;
+        }
+        if(m) *s-- = '-';
+        *s-- = 'E';
+    }
+    // now our number is in [1, 1000]
+    uint32_t units;
+    if(prec){
+        units = (uint32_t) x;
+        uint32_t decimals = (uint32_t)((x-units+rounds[prec])*pwr10[prec]);
+        // print decimals
+        while(prec){
+            int d10 = decimals / 10;
+            *s-- = '0' + (decimals - 10*d10);
+            decimals = d10;
+            --prec;
+        }
+        // decimal point
+        *s-- = '.';
+    }else{ // without decimal part
+        units = (uint32_t) (x + 0.5);
+    }
+    // print main units
+    if(units == 0) *s-- = '0';
+    else while(units){
+            uint32_t u10 = units / 10;
+            *s-- = '0' + (units - 10*u10);
+            units = u10;
+        }
+    if(minus) *s-- = '-';
+    return s+1;
+}
+
+char *getfloat(char *str, float *f){
+    str = omit_spaces(str);
+    int isminus = 0;
+    if(*str == '-'){
+        isminus = 1;
+        ++str;
+    }else if (*str == '+'){
+        ++str;
+    }
+    float result = 0.0f;
+    while(*str >= '0' && *str <= '9'){
+        result = result * 10.0f + (float)(*str - '0');
+        ++str;
+    }
+    if(*str != '.') goto retn;
+
+    ++str; // omit point
+    float frac = 0.0f;
+    float divisor = 1.0f;
+
+    while(*str >= '0' && *str <= '9'){
+        divisor *= 10.0f;
+        frac = frac * 10.0f + (float)(*str - '0');
+        ++str;
+    }
+
+    if(divisor > 1.0f){
+        result += frac / divisor;
+    }
+
+    if(*str == 'e' || *str == 'E'){ // exp
+        ++str;
+        int32_t E;
+        if(str != getint(str, &E)){
+            if(E > 0) while(E-- > 0) result *= 10.f;
+            else while(E++ < 0) result /= 10.f;
+        }
+    }
+
+retn:
+    if(f) *f = (isminus) ? -result : result;
+    return str;
+}
+