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Assignments

Read the ‘overzicht’ document!

Aan wouter.vanooijen@hu.nldaniel.telgen@hu.nl

Onderwerp V2CCPP1 x yx = student nummer y = nummer van de opgave, 1..12

Bijlage De uitwerking. Als de uitwerking meerdere file beslaat moet de bijlage een .zip file zijn. Geen andere compressie formaten gebruiken!

Body Geen eisen

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C lessons

Lesson Subject Book

Week 1 lesson 1 Objects, names

Week 1 lesson 2 Statements, layout

Week 2 lesson 1 Functions, decomposition

Week 2 lesson 2 Lists, specification

Week 3 lesson 1 Memory, testing

Week 3 lesson 2 Fagan inspection

The most important way to structure your program The most important things to name The most important things to reuse

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C function

Interface: name argument list return type

Interface only declaration With body definition (== implementation)

The name identifies the function: two visible functions can not have the same name (!= C++)

The argument list must match the actual arguments passed in each call (in number and type)

int give_me_eight( void ){

return 8;

}

int give_me_eight( void );

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Result Is what is after the executed ‘return’ statement Return behaves as an assignment to an invisible variable. Is the result of the function call

Parameters and result

Formal parameters are mentioned in the interface Used in the body (implementation)

int add( int a, int b ){

return a + b;

}

int x = add( a, 8 ); Actual parameters Is what you (the caller) supply when you can a function Are (sort-of) assigned to the formal parameters

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Parameter passing – by value

Basic types are passed ‘by value’ void g( char c, int i, float f, int *p ){

c = 'a';

i = 5;

f = 10.0;

p = NULL;

}

int main( void ){

char c = 'x';

int i = 0;

float f = 0.0;

int *p = &i;

printf( "%c %d %f %d \n", c, i, f, (int)p );

g( c, i, f, p );

printf( "%c %d %f %d \n", c, i, f, (int)p );

}

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Parameter passing - pointers

To change a basic type: pass a pointer to itvoid g( char *c, int *i, float *f, int **p ){

*c = 'a';

*i = 5;

*f = 10.0;

*p = NULL;

}

int main( void ){

char c = 'x';

int i = 0;

float f = 0.0;

int *p = &i;

printf( "%c %d %f %d \n", c, i, f, (int)p );

g( &c, &i, &f, &p );

printf( "%c %d %f %d \n", c, i, f, (int)p );

}

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Parameter passing - arrays

Arrays are invisibly passed ‘by reference’ == ‘by address’void f( int a[ 5 ] ){

a[ 0 ] = 5;

a[ 1 ] = 4;

a[ 2 ] = 3;

a[ 3 ] = 2;

a[ 4 ] = 1;

}

int main( void ){

int a[ 5 ] = { 1, 2, 3, 4, 5 };

printf( "%d %d %d %d %d \n", a[0], a[1], a[2], a[3], a[4] );

f( a );

printf( "%d %d %d %d %d \n", a[0], a[1], a[2], a[3], a[4] );

}

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Parameter passing – array size

Array parameters can either be Of a specific size Without a specific size

Without a specific size, you will need some other way to find out how large the array is (or you will create the next buffer overrun exploit..)

void f( int a[ 5 ] ){

int i;

for( i = 0; i < 5; i++ ){

...

}

}

void f( int a[] ){

int i;

for( i = 0; i < ??; i++ ){

...

}

}

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Function pointers – pass ‘work’ around

#include <stdio.h>

typedef int (*int_filter)( int );

int add1( int x ){ return x + 1; }

int clip10( int x ){ return x > 10 ? 10 : x; }

int absolute( int x ){ return x > 0 ? x : -x; }

void apply_int_filter( int a[], int size, int_filter f ){

int i; for( i = 0; i < size; i++ ){

a[ i ] = f( a[ i ] );

}

}

void array_print( int a[], int size ){

int i; for( i = 0; i < size; i++ ){

printf( "%4d ", a[ i ] );

}

printf( "\n" );

}

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Function pointers – pass ‘work’ around

int main( void ){

#define a_size 7

int a[ a_size ] = { -1, -2, 0, 1, 2, 10, 100 };

array_print( a, a_size );

apply_int_filter( a, a_size, add1 );

array_print( a, a_size );

apply_int_filter( a, a_size, clip10 );

array_print( a, a_size );

apply_int_filter( a, a_size, absolute );

array_print( a, a_size );

system("PAUSE");

return 0;

}

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A simple NDS paint application

#configure board ndsi

#configure emulator desmume

#include <nds.h>

#include <nds/touch.h>

#include "lcd.h"

int main( void ){

struct touchPosition position;

nintendo_screen lcd;

lcd.clear( colors::red );

for(;;){

scanKeys();

int held = keysHeld();

if( held & KEY_TOUCH ){

touchRead( & position );

lcd.pixel_write( position.px, position.py, colors::black );

}

swiWaitForVBlank();

}

return 0;

}

mkt.py info

libndsgraphics lib

Lcd lib ‘init’

poll the keys

read stylus

f = 60 Hz

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Paint within an area#define rx0 10

#define ry0 10

#define rx1 200

#define ry1 180

int position_is_in_rectangle( int x, int y, int x0, int y0, int x1, int y1 ){

return( x > x0 && x < x1 && y > y0 && y < y1 );

}

int main( void ){

struct touchPosition position;

nintendo_screen lcd;

lcd.clear( colors::red );

lcd.rectangle_write( rx0, ry0, rx1, ry1 );

for(;;){

scanKeys();

int held = keysHeld();

if( held & KEY_TOUCH ){

touchRead( & position );

if( position_is_in_rectangle(

position.px, position.py, rx0, ry0, rx1, ry1

)){

lcd.pixel_write( position.px, position.py, colors::blue );

}

}

swiWaitForVBlank();

}

return 0;

}

rectangle

check

function

show

paint

only when

within

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But we want more

The paint area is just one ‘object’ on the screen.

We want more, like changing the brush color.

Because (re)drawing and the action are separated we must specify the coordinates twice .

Build a list of ‘active objects’.

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Paint - a list of objects

typedef struct area_struct area;

typedef void ( *action )( int x, int y, area *a );

struct area_struct {

area *next;

int x0, y0, x1, y1;

action f;

};

area *first = NULL;

void area_add( int x0, int y0, int x1, int y1, color fill, action f ){

area *p = (area*) malloc( sizeof( area ));

p->x0 = x0;

p->x1 = x1;

p->y0 = y0;

p->y1 = y1;

p->f = f;

lcd.rectangle_write( x0, y0, x1, y1, colors::black, fill );

p->next = first;

first = p;

}

‘forward’

object

linked list of objects

Create an object and chain it.

Q: this is not quality code. Why?

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Paint – create the list

void execute( int x, int y ){

area *p;

for( p = first; p!= NULL; p = p->next ){

if( position_is_in_rectangle( x, y, p->x0, p->y0, p->x1, p->y1 )){

p->f( x, y, p );

}

}

}

color active_color = colors::blue;

void paint( int x, int y, area *a ){

lcd.pixel_write( x, y, active_color );

}

void select_red( int x, int y, area *a ){

active_color = colors::red;

}

void select_green( int x, int y, area *a ){

active_color = colors::green;

}

void select_blue( int x, int y, area *a ){

active_color = colors::blue;

}

Check, maybe excute

global

change-color actions

draw-box action

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Paint - main

int main( void ){

struct touchPosition position;

lcd.clear( colors::yellow );

area_add( 10, 10, 200, 180, colors::white, paint );

area_add( 210, 10, 220, 20, colors::red, select_red );

area_add( 210, 25, 220, 35, colors::green, select_green );

area_add( 210, 40, 220, 50, colors::blue, select_blue );

for(;;){

scanKeys();

int held = keysHeld();

if( held & KEY_TOUCH ){

touchRead( & position );

execute( position.px, position.py );

}

swiWaitForVBlank();

}

return 0;

}

Create list

Execute list

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IDE

Make sure you have copied or installed devkitPro (in C:\devkitPro) DeSuME (in C:\devkitPro\sim\DeSmuME) Python (2.5, 26, 3.0, 3.1, etc) PSPad

get the week-2-1-paint.zip, unzip to a directory, no spaces in the path name !!

Double-click Project.ppr

devkitPro.zip

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IDE

Compile, link, build, run simulator

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Assignment

Create an NDS GUI for the reversi code. Use week-2-1-reversi.zip Use you own reversi code

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Assignment - list

struct area_struct {

area *next;

int field;

int x0, y0, x1, y1;

action f;

};

void area_add( int field, int x0, int y0, int x1, int y1, action f ){

area *p = (area*) malloc( sizeof( area ));

p->x0 = x0;

p->x1 = x1;

p->y0 = y0;

p->y1 = y1;

p->field = field;

p->next = first;

p->f = f;

first = p;

}

Field (0..99)

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Assignment - main

int main( void ){

struct touchPosition position;

init_reversi();

redraw();

for(;;){

scanKeys();

int held = keysHeld();

if( held & KEY_TOUCH ){

touchRead( & position );

execute( position.px, position.py );

redraw();

}

swiWaitForVBlank();

}

return 0;

}

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Assignment – reversi GUI

nintendo_screen lcd;

int side_to_move = black;

board global_board;

int other_side( int x ){ return x == black ? white : black; }

color side_color( int side ){ return side == black ? colors::blue : colors :: red; }

void try_move( int x, int y, area * a ){ }

void redraw_square( area * a ){ }

void redraw( void ){ }

void init_reversi( void ){

int i, x, y;

const int width = 18;

reversi_board_init( global_board );

for( i = 0; i < 100; i++ ){

x = 5 + (( i / 10 ) * width );

y = 5 + (( i % 10 ) * width );

area_add( i, x, y, x + width, y + width, try_move );

}

}

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Assignment

Function # Lines in my version Remarks

try_move 8 If the move is allowed (for the current side-to-move) do it, and update side_to_move.

redraw_square 26(lots of folded lines)

Redraw the border around the square. Draw fill for border, empty square. Draw the tile within an occupied square.

redraw 12 Clear LCDRedraw all squares (call redraw_square to do the work)Redraw ‘side to move’ indicator

What if the current side-to-move has no legal moves?