Hi guys, I am using a #define to do a calculation during compile time and load the result in an (8 bit) uart register so that I can set the baudrate.
I am using the following in a header file : #define crystal 11059200 #define bd4800 (256 - crystal / 192 * 4800) Here the result is 0xef854100 #define crystal 11059200 #define bd4800 (256 - (crystal / 921600)) And here the (correct) result is 0xf4 Why is it that the multiplication in the first #define fails ? I have used brackets "()" in numerous places, did typecasts, split up the #define in multiple parts but all failed on the multiplication. It seems that when I use a multiplication the result stored in the #define is limited to a signed 16 bit number. Is this assumption correct ? Update : I have done some further tests and the assumption seems correct for a multiplication. If I do the following division #define (crystal / 100) the answer is 0x0001b000 which is correct. I am using SDCC : mcs51 3.2.1 #8413 (8 Feb 2013) (Linux) The command line is : sdcc -D_89v664 -c --model-small --code-size 65536 --xram-size 2048 serial.c Thanks. roelof ------------------------------------------------------------------------------ Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb _______________________________________________ Sdcc-user mailing list Sdcc-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sdcc-user
