OSDev.org

Code: Select all

char *convertStringToInt(int *number, char *string) {
    if(strncasecmp(string, "0x", 2) == 0) {
        // Hexadecimal
        return convertStringToIntWithBase(number, &string[2], 16);
    }
    if(*string == '0') {
        // Octal???
        return convertStringToIntWithBase(number, &string[1], 8);
    }
    // Decimal
    return convertStringToIntWithBase(number, string, 10);
}


char *convertStringToIntWithBase(int *number, char *string, int base) {
    int digit;

    *number = 0;

    for(;;) {
        if( (*string >= '0') && (*string <= '9') )  {
            digit = *string - '0';
        } else if( (*string >= 'A') && (*string <= 'Z') )  {
            digit = *string - 'A' + 10;
        } else if( (*string >= 'a') && (*string <= 'z') )  {
            digit = *string - 'a' + 10;
        } else {
            break;
        }
        if(digit >= base) {
            break;
        }
        if(*number >= INT_MAX / base) {
            return NULL; // Will overflow...
        }
        *number = *number * base;
        if(*number >= INT_MAX - digit) {
            return NULL; // Will overflow...
        }
        *number = *number + digit;
        string++;
    }
    return string;
}

Code: Select all

int atodw(const char *str) {
    int value = 0;

    for(int counter = strlen(str)-1, multiplier = 1; !(counter < 0); --counter, multiplier *= 10) {
        value += (str[counter] - 0x30) * multiplier;
    }
   
    return value;
}

Code: Select all

; --------------------------------------------------
  __StrToDWORD:
    ; DWORD __StrToDWORD (const char* InStr)
    PUSH    EBX
    PUSH    EDX
    PUSH    EBP
    MOV     EBP , ESP
    MOV     EBX , DWORD PTR [EBP + 0x10]
    XOR     EAX , EAX
    .Loop:
      MOV     EDX , DWORD PTR [EBX]
      AND     EDX , 0x000000FF
      JE      .EP
      AND     EDX , 0x0000000F
      ADD     EAX , EAX
      LEA     EAX , [EAX + 0x04*EAX]
      ADD     EAX , EDX
      INC     EBX
      JMP     .Loop
    .EP:
      POP     EBP
      POP     EDX
      POP     EBX
    RET     0x04
; --------------------------------------------------