topic Re: CodeWarriro don`t support 16-bit multiply 16-bit in CodeWarrior for MCU

CodeWarriro don`t support 16-bit multiply 16-bit

CASEYKEVIN — Wed, 23 Feb 2011 09:42:31 GMT

in my application, i need operation of 16-bit * 16-bit

volatile dword mytempDword;

volatile word mytempword1 = 300;

volatile word mytempword2= 312;

main()

{

...

mytempDword = mytempword1 * mytempword2;

}

Codewarriror gives wrong result of 28064, but the correct result is 93600, i found that 93600 = 65536 + 28064 , obviously, the 16th bit is ignored by CodeWarrior. why? my setting options of CodeWarrior is default. and CodeWarriror version is 5.9

Anybody here know why? thanks

regards

Re: CodeWarriro don`t support 16-bit multiply 16-bit

rocco — Wed, 23 Feb 2011 10:49:10 GMT

Hi CaseyKevin,

A word can hold an unsigned number from 0 to 65535, or a signed number from -32768 to +32767.

The number 93600 would require at least 17 bits.

If you cast the words into dwords before you multiply, you should get the correct result.

Re: CodeWarriro don`t support 16-bit multiply 16-bit

CASEYKEVIN — Wed, 23 Feb 2011 14:09:51 GMT

follow you advices, i get the correct result

thanks very much