SW500007 Microchip Technology, SW500007 Datasheet - Page 75

• Manufacturer Part Number: SW500007
• Description: PICC-18 PRO
• Manufacturer: Microchip Technology
• Type: Compilerr
• Series: PIC18r

Specifications of SW500007

• Supported Families: PIC18
• Core Architecture: PIC
• Software Edition: Professional
• Kit Contents: Software And Docs
• Mcu Supported Families: PIC18
• Tool Function: Compiler
• Tool Type: Compiler
• Lead Free Status / RoHS Status: Not applicable / RoHS Compliant
• For Use With/related Products: PIC18 Series
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 015P; 778-1002; 778-1002

C Language Features
The unsigned char result of a - b is 206 (which is not less than 10), but both a and b are con-
verted to signed int via integral promotion before the subtraction takes place. The result of the
subtraction with these data types is -50 (which is less than 10) and hence the body of the if() state-
ment is executed. If the result of the subtraction is to be an unsigned quantity, then apply a cast.
For example:
The comparison is then done using unsigned int, in this case, and the body of the if() would not be
executed.
operator toggles each bit within a value. Consider the following code.
If c contains the value 55h, it often assumed that ~c will produce AAh, however the result is FFAAh
and so the comparison above would fail. The compiler may be able to issue a mismatched compari-
son error to this effect in some circumstances. Again, a cast could be used to change this behaviour.
with char-type operands, but with int-type operands. However there are circumstances when the
result of an operation is identical regardless of whether the operands are of type char or int. In
these cases, HI-TECH PICC-18 STD will not perform the integral promotion so as to increase the
code efficiency. Consider the following example.
Strictly speaking, this statement requires that the values of b and c should be promoted to unsigned
int, the addition performed, the result of the addition cast to the type of a, and then the assignment
can take place. Even if the result of the unsigned int addition of the promoted values of b and c
was different to the result of the unsigned char addition of these values without promotion, after
the unsigned int result was converted back to unsigned char, the final result would be the same.
An 8-bit addition is more efficient than a 16-bit addition and so the compiler will encode the former.
to be performed to comply with the ANSI standard.
Another problem that frequently occurs is with the bitwise compliment operator, “~”. This
The consequence of integral promotion as illustrated above is that operations are not performed
If, in the above example, the type of a was unsigned int, then integral promotion would have
if((unsigned int)(a - b) < 10)
unsigned char count, c;
c = 0x55;
if( ~c == 0xAA)
unsigned char a, b, c;
a = b + c;
count++;
count++;
Operators
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