MAKING THE NUMBERS WORK FOR YOU

THE MAGAZINE FOR COMPUTER APPLICATIONS
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MAKING THE NUMBERS WORK FOR YOU

Lessons from the Trenches by George Martin

Start ı Stating Our Case ı Working the Wiring ı A Case Study in Timer Interrupts ı Sources and PDF

Last month, I gave you a foundation in signed and unsigned binary numbers and how the compilers, assembly language, and CPUs support them. This month, Iıd like to talk about how you can use these signed and unsigned numbers to your advantage.

WORTHY OF REPEATING

Remember, itıs good practice to use #typedefs so youıre sure of the size of data being referenced. Letıs assume you are writing code for a 16-bit CPU and your compiler defines a char as 8 bits, int as 16 bits, and long as 32 bits. Table 1 shows the typedefs that would be set up.

#typedef

CHAR8

UCHAR8

INT16

UINT16

INT32

UINT32

char

unsigned char

int

unsigned int

long

unsigned long

Table 1ıHere you can see the typedefs that would be set up for a 16-bit CPU with char as 8 bits, int as 16 bits, and long as 32 bits.

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