long_int multiply(long_int num1, long_int num2)
{
int digits1 = numDigits(num1);
int digits2 = numDigits(num2);
if(digits1 == 1 || digits2 == 1)
{
return num1 * num2;
}
long_int a = rightShift(num1, (digits1/2));
long_int c = rightShift(num2, (digits2/2));
long_int b = getSuffix(num1, digits1/2);
long_int d = getSuffix(num2, digits2/2);
long_int ac = multiply(a, c);
long_int bd = multiply(b, d);
long_int aplusbtimescplusd = multiply(a + b, c + d);
long_int cof1 = tenPower((digits1/2) + (digits2/2));
long_int cof2 = tenPower(digits1/2);
long_int sum_term_1 = cof1 * ac;
long_int sum_term_2 = cof2 * (aplusbtimescplusd - ac - bd);
return (sum_term_1 + bd + sum_term_2);
}
void multiply_bignum(bignum *a, bignum *b, bignum *c)
{
bignum aCopy = *a;
bignum tmp;
int i, j;
int digit;
// TODO: compare a and b for the optimized performance.
if (compareBignum(a, b) < 0)
{
multiply_bignum(b, a, c);
return;
}
initializeBignum(c);
rightShift(&aCopy, b->numFractions);
// Multiple by the fractional numbers.
for (i = 0; i < b->numFractions; i++)
{
digit = b->integers[i];
// Add {digit} times.
for (j = 1; j <= digit; j++)
{
addBignum(c, &aCopy, &tmp);
*c = tmp;
}
leftShift(&aCopy, 1);
}
// Multiple by the integer numbers.
for (i = 0; i <= b->numIntegers; i++)
{
digit = b->integers[i];
for(j = 1; j <= digit; j++)
{
addBignum(c, &aCopy, &tmp);
*c = tmp;
}
leftShift(&aCopy, 1);
}
c->sign = (a->sign == b->sign) ? PLUS : MINUS;
optimizeBignum(c);
}
void input (void)
{
int c;
u64 x;
u64 new_block = 0;
NewNumber = TRUE;
Radix = HEX;
output();
for (;;) {
if (new_block != BlockNum) {
if (readDisk(new_block) != 0) {
new_block = BlockNum;
}
}
output();
c = getch();
switch (c) {
/*
* Don't use these: CNTRL(C), CNTRL(Z), CNTRL(S),
* CNTLR(Q), CNTRL(Y)
*/
case '?': help(); break;
case '_': lastx(); neg(); break;
case '+': lastx(); add(); break;
case '-': lastx(); sub(); break;
case '*': lastx(); mul(); break;
case '/': lastx(); divide(); break;
case '%': lastx(); mod(); break;
case '~': lastx(); not(); break;
case '&': lastx(); and(); break;
case '|': lastx(); or(); break;
case '^': lastx(); xor(); break;
case '<': lastx(); leftShift(); break;
case '>': lastx(); rightShift(); break;
case '.': lastx(); swap(); break;
case '!': lastx(); store(); break;
case '=': lastx(); retrieve(); break;
case '#': lastx(); qrand(); break;
case KEY_RESIZE: /* Screen resize event - don't do anything */
break;
case KEY_LEFT:
case 'h': Current->left(); /* left one column */
break;
case KEY_DOWN:
case 'j': Current->down(); /* down one row */
break;
case KEY_UP:
case 'k': Current->up(); /* up one row */
break;
case KEY_RIGHT:
case 'l': Current->right(); /* right one column */
break;
case CNTRL('A'):clear(); /* switch to next format */
next_format();
break;
case CNTRL('W'):clear(); /* switch to previous format */
prev_format();
break;
case CNTRL('B'):/* Backward one block */
if (BlockNum > 0) {
new_block = BlockNum - 1;
}
break;
case EOF: /* Ignore EOF - send on resize */
break;
case 'q':
case CNTRL('D'):finish(0); /* Exit */
break;
case CNTRL('F'):/* Forward a block */
new_block = BlockNum + 1;
break;
case 'g': /* Go to specified Block */
lastx();
x = pop();
NewNumber = FALSE;
new_block = x;
break;
case KEY_BACKSPACE:
case KEY_DC:
case CNTRL('H'):/* Delete last digit entered */
push(pop() / RadixTable[Radix]);
break;
case CNTRL('I'):/* Next field */
Current->next();
break;
case KEY_CLEAR:
case CNTRL('L'):/* Refresh the display */
wrefresh(curscr);
break;
case KEY_ENTER:
case CNTRL('M'):/* Finish entry of number or duplicate top */
if (!NewNumber) {
duptop();
}
NewNumber = FALSE;
break;
case CNTRL('P'):/* Push copy of current field */
Current->copy();
NewNumber = FALSE;
break;
case CNTRL('R'):/* Rotate from bottom of stack to top */
rotate();
break;
case 'r': /* Change radix */
++Radix;
if (Radix > UNSIGNED) Radix = HEX;
break;
case CNTRL('T'):/* Reinitialize stack */
initStack();
NewNumber = TRUE;
break;
case CNTRL('U'):/* Push last x */
push(Lastx);
NewNumber = FALSE;
break;
case CNTRL('X'):/* Delete top of stack */
(void)pop();
push(0);
NewNumber = TRUE;
case 'Z': /* Previous field */
Current->prev();
break;
default: /* Is it a digit? */
if ((Radix == HEX) && isxdigit(c)) {
if (isdigit(c)) {
digit(c, '0');
} else if (isupper(c)) {
digit(c, 'A' - 10);
} else {
digit(c, 'a' - 10);
}
} else if ((Radix == UNSIGNED) && isdigit(c)) {
digit(c, '0');
} else if ((Radix == SIGNED) && isdigit(c)) {
digit(c, '0');
} else if (Radix == CHARACTER) {
digit(c, 0);
} else {
flash();
sprintf(Error, "bad char=%d", c);
}
break;
}
}
}
//right shift base Decimal
BigInt& BigInt::selfRightShift(size_t n)
{
BigInt bi = rightShift(n);
*this = bi;
return *this;
}