Imagecraft c compiler and development environment for the atmel avr

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ICCV8 for AVR – C Compiler for Atmel AVRTable 1:Suffix Decimal Constant Octal / Hex Constantnoneu or Uintlong intunsigned intunsigned long intintunsigned intlong intunsigned long intunsigned intunsigned long intl or L long int long intunsigned long intboth u/U and l/L unsigned long int unsigned long intExpressionsExpression statements are where things happen. Every expression produces a valueand may contain side effects. In standard C, you can mix and match expressions ofdifferent data types and, within certain rules, the compiler will convert the expressionsto the right type for you. Integer and floating-point expressions can be used togetherand, in most cases, the expected things happen. A case where the unexpected mayhappen is where the type of an expression solely depends on the types of itsoperands and not how on they will be used. For example:long_var = int_var1 * int_var2; // int multiplylong_var = (long)int_var1 * int_var2; // long multiplyThe first multiplication is done as an integer multiply and not as a long multiply. If youwant long multiply, at least one of the operands must have the type long, as seen inthe second example. This also applies to assigning to floating-point variables, etc. aswell.Another point of note is that the C standard says that operands are promoted toequivalent types before the operation is done. In particular, an integer expressionmust be promoted to at least int type if its type is smaller than an int type. However,the “as-if” rule says that the promotion does not need to physically occur if the result isthe same. Our compilers will try to optimize the byte-sized operations wheneverpossible. Some expressions are more difficult to optimize, especially if they producean intermediate value. For example,78
ICCV8 for AVR – C Compiler for Atmel AVRchar *p;...... *p++...The compiler may not be as optimal, since *p is a temporary value that needs to bepreserved.OperatorsC has a rich set of operators, including bitwise operators that make handling IOregisters easy. There is no “logical” or “boolean” type per se, so any non-zero value istaken as “true.” You may intermix any operators, including logical, bit-wise, etc., in anexpression. The following lists the operators from high to lower precedence. Withineach row, the operators have the same precedence.Table 2: Operator Precedence and AssociativityOperators() function call[] array element-> structure pointer field dereference. structure field reference! logical not~ one’s complement++ pre/post increment-- pre/post decrement+ unary plus- unary minus* pointer dereference& address of(type) type castsizeof size of type* multiply/ divide% remainder+ addition- subtractionAssociativityleft to rightright to leftleft to rightleft to right79
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TOOL REFERENCESMISRA / Lint Code Ch
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Imagecraft c compiler and development environment for the atmel avr

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