On Apr 4, 2005 12:46 PM, Hans Petter Selasky <[EMAIL PROTECTED]> wrote:
Hi,
How much does the multiplication circuits impact on price/power/heat/speed?
Will it be worth optimizing multiplication like this (in FPGA, expanding the
while loop):
/*
* multiplication without having to
* wait for the carry to complete
*/
u_int32_t
multiply_1(u_int32_t a, u_int32_t b, u_int32_t remainder)
{
u_int32_t carry = 0;
u_int32_t temp = remainder;
u_int32_t old;
/* step 1
* convert b into a
* +-0+00-0+- string
* which is parity
*/
b ^= 2*b;
/* step 2
* multiply
*/
while(b)
{
if(b & 1)
{
old = carry;
carry = temp;
temp = a | old;
}
temp ^= carry;
carry &= temp;
/*
* new carry is 0 under temp == 1.
* That is why (a | old) is possible.
*/
b /= 2;
a *= 2;
carry *= 2;
temp *= 1;
}
/* step 3
* subtract rest of carry
*/
temp -= carry;
return temp;
}
Please CC me, hence I'm not on the list.
Yours
--HPS
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