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multiplication ***int32 | Cypress Semiconductor

multiplication ***int32

Summary: 2 Replies, Latest post by danaaknight on 23 Jul 2012 05:22 AM PDT
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gopal's picture
6 posts


i couldn't acquire a uint32 multiplication with the following code  (psoc creator),  it calculates wrongly some value. whats my mistake.














user_189995688's picture
138 posts

  The compiler by deafault will treat the constants as 'int' and then do a basic 'integer' multiplication, storing the result into the uint32.

You need to tell the compiler how to treat the constants, something like using an integer suffix like this:


ball = 4ul x 24ul x 3200ul;

user_14586677's picture
7646 posts

I learned something from this post, reference material -


Integer constants

  • Integer constants can be one of the different bases:
    • a number starting with a digit from 1 to 9 followed only by digits from 0 to 9 is a decimal (base 10) constant, like 1 or 54321
    • if a number begins with '0x' or '0X' and is followed by digits from 0 to 9 and letters from a to f or from A to F, it is interpreted as a hexadecimal (base 16) constant, like 0xbeef or 0XDEAD
    • if a number begins with 0 and is followed by digits from 0 to 7, it is interpreted as an octal (base 8) constant, like 07 (which is the same as 7) or 0111 (which is NOT the same as 111)
  • integer constants in any of the three bases may be followed by an 'l' or 'L' to indicate a long constant, like 17l or 0xFfL
  • in ANSI C, an integer constant may be followed by:
    • a 'u' or 'U' to indicate an unsigned constant, like 33u
    • a 'ul' or 'UL' to indicate an unsigned long constant, like 32767ul
  • an integer constant takes on the minimum type necessary to be accurately represented, (possibly) starting as int and increasing from long to unsigned long
    • octal and hexadecimal constants, and (in ANSI C) constants ending with a 'u' or 'U' may also be unsigned (which can hold larger values than int but may have fewer bytes than long)
  • in ANSI C, 0 is always unsigned (perhaps to reduce ambiguity on machines with one's complement arithmetic)
  • as an example, if an int is 16 bits wide and a long is 32 bits wide, the following ranges would apply:
    Range			Decimal		Octal/Hexadecimal
    0			unsigned	unsigned
    1-32767			int		int
    32768-65535		long		unsigned
    65536-2147483647	long		long
    2147483648-429497295	unsigned long	unsigned long
    429497296-?		???		???

Regards, Dana.

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