stm32samples/F0:F030,F042,F072/Snippets/readint.c

char *omit_spaces(char *buf){
    while(*buf){
        if(*buf > ' ') break;
        ++buf;
    }
    return buf;
}

// THERE'S NO OVERFLOW PROTECTION IN NUMBER READ PROCEDURES!
// read decimal number
static char *getdec(char *buf, uint32_t *N){
    uint32_t num = 0;
    while(*buf){
        char c = *buf;
        if(c < '0' || c > '9'){
            break;
        }
        num *= 10;
        num += c - '0';
        ++buf;
    }
    *N = num;
    return buf;
}
// read hexadecimal number (without 0x prefix!)
static char *gethex(char *buf, uint32_t *N){
    uint32_t num = 0;
    while(*buf){
        char c = *buf;
        uint8_t M = 0;
        if(c >= '0' && c <= '9'){
            M = '0';
        }else if(c >= 'A' && c <= 'F'){
            M = 'A' - 10;
        }else if(c >= 'a' && c <= 'f'){
            M = 'a' - 10;
        }
        if(M){
            num <<= 4;
            num += c - M;
        }else{
            break;
        }
        ++buf;
    }
    *N = num;
    return buf;
}
// read binary number (without 0b prefix!)
static char *getbin(char *buf, uint32_t *N){
    uint32_t num = 0;
    while(*buf){
        char c = *buf;
        if(c < '0' || c > '1'){
            break;
        }
        num <<= 1;
        if(c == '1') num |= 1;
        ++buf;
    }
    *N = num;
    return buf;
}

/**
 * @brief getnum - read uint32_t from string (dec, hex or bin: 127, 0x7f, 0b1111111)
 * @param buf - buffer with number and so on
 * @param N   - the number read
 * @return pointer to first non-number symbol in buf (if it is == buf, there's no number)
 */
char *getnum(char *txt, uint32_t *N){
    if(*txt == '0'){
        if(txt[1] == 'x' || txt[1] == 'X') return gethex(txt+2, N);
        if(txt[1] == 'b' || txt[1] == 'B') return getbin(txt+2, N);
    }
    return getdec(txt, N);
}