s3 c Programming

8/9/2019 s3 c Programming

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Programming The

Encore using ANSI C


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Outline

1. Project structure: Source files, include files

2. C data types and derived types

3. Looping (while, for, do-while)4. Viewing variables in the debugger

5. Conditional flow (if-then and switch)

6. Shorthand

7. Functions and parameter-passing8. Debugging functions

9. Multi-file projects


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Project structure Project

uC selection

Editor settings

Debugger settings

Source files

External dependencies Include files

Object code libraries


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Source files Typically main.c

contains the main()

function, where executionstarts

Split program up into

several functions

Often one function for each

source file


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External dependencies Declared by #include

Include files that declare std C functions, e.g. stdio.h (standard I/O, e.g. printf, scanf) math.h (e.g. sin, exp, rand)

Include files for uC-specific info eZ8.h

Declared by #include filename

Include files for user-defined functions

User-created object files


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C Data Types Character (8-bits)

char c1, c2;

c1 = a; c2 = \n; Integer (16-bits)1

int i;

i = -20; // a decimal number

Floating point (32-bits)float f1, f2;

f1 = 2.3; f2 = 1.5e3;

1by default, short is the same as int


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C Data Types Byte (8-bits)

unsigned char a,b;

a = 0xaf; b = 128; Word (16-bits)

unsigned int i;

i = 0xffff; // hexadecimal FFFFh

Long (32-bits)long i;

i = -100000;


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C Derived TypesArray

int tbl[5];

tbl[0] = 3; tbl[4] = -1;

String

char * name = Encore;

name[0] = I;

(name will now contain Incore)


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Conditionalif

if (i==1)

ch = y;

else

ch = n;

if (i>0) f = f+1;

if (i>=j) {temp = i; i = j; j = temp;

}


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Conditionalswitch

switch (val) {

case 1:

ch = q; break;

case 2:

ch = z; break;

default:ch = x; break;

}


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whileLoops

int tbl[5]={3,2,-1,4,6}, sum, i;

sum = 0;

i = 0;

while (i


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forand

do-whileloops

for loopssum = 0;

for (i=0; i


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Other operations

Math +, -, *, /, % (remainder)

Logical ! (not), && (and), || (or)

Comparison

=, == (equal), != (not equal) Bitwise

~ (not), & (and), | (or), ^ (xor),>> (right shift),


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Logical and bitwise opsint a=0xf0, b=0x21, c, d, e;

c = a & b;

d = a && b;

e = b


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Shorthand Increment/Decrement

int i,j,k;

i = 3;

j = i++;

k = ++i;

Accumulator operations

i += 4;

PAOUT |= 0x0f;

PAOUT &= 0xfb;

j will be 3; i will be 4

k will be 5; i will be 5

Sets lower nibble of PAOUT high

Sets bit 2 (3rd bit) of PAOUT low

Equivalent to i=i+4; i will be 9


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Functionsdelay() {

}

main() {

while (1) {

delay();

}

}


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Passing argumentsdelay(int imax) {

int i,j;

for (i=0; i


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Returning argumentsfloat getfreq(int ch) {

return clkfreq/count;

}

main() {

float freq;freq = getfreq(1);

}


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Why use functions?

Re-use code

Keep size of each function small,especially main() Rule of thumb: < 100 lines

Can repeat variable names for local use

If placed in separate files, functions can becompiled separately Speeds up overall compilation Faster debugging cycle

Necessary for vectored interrupts


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Debugging functionsStep into:Enter and

debug thesubroutine

Step over:Execute thesubroutine

Step into (F11)

Step over (F10)


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BreakpointsRight-click on the line of interest,

Select Insert Breakpoint

Breakpoint is set

Execution will stop at thebreakpoint


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Placing functions

in separate files The clean way (easier to debug)

Put functions in a separate .c file in your project

folder Put function prototypes in a separate .h file

Function header w/o the body

E.g. void delay(int imax);

Add the .c file to your project files list Put #include statements

In source code files that use your function

In the file where your function is completely written


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Placing functions

in separate files

#include looks for xx in a special ZDS directory#include xx looks for xx in your project folder

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s3 c Programming