Water tank application
[Applications]

The water tank application is a process control-inspired demonstration of the slider, progress bar and command button widgets in the Widget toolkit; bitmaps of the Graphics display system; and basic use of the Window toolkit. More...

Collaboration diagram for Water tank application:

Data Structures
struct	tank_context
	Context for the water tank application. More...
Enumerations
enum	tank_loader_state { LOAD_RED_LIGHT, LOAD_GREEN_LIGHT, LOAD_BACKGROUND, LOAD_FINISHED }
	States for the application loader task. More...
enum	tank_bitmap_id { BITMAP_RED_LIGHT, BITMAP_GREEN_LIGHT, NR_OF_BITMAPS }
	Enumeration of bitmaps to load to hugemem. More...
enum	tank_command_id { CMD_NONE, CMD_EXIT }
	Event command ID for application widgets. More...
Functions
static bool	tank_frame_handler (struct wtk_basic_frame *basic_frame, win_command_t command_data)
	Command event handler for the application's frame.
static int32_t	tank_logistic_map (int32_t rand)
	Compute new random value via a logistic map.
static void	tank_worker (struct workqueue_task *task)
	Application worker function.
static void	tank_timer_callback (struct timer *timer)
	Application timer callback function.
static void	tank_loader (struct workqueue_task *task)
	Application loader.
void	app_tank_launch (struct workqueue_task *task)
	Launch the water tank application.
Variables
static hugemem_ptr_t	tank_bitmap_data [NR_OF_BITMAPS]
	Pointers to bitmap data in hugemem.
static struct tank_context *	tank_ctx
	Pointer to water tank application context.
Color scheme

#define	COLOR_WIN_BACKGROUND GFX_COLOR(0, 0, 0)
	Color to initially fill screen with.
#define	COLOR_LEVEL_FILL GFX_COLOR(0, 0, 255)
	Fill color for tank level indicator.
#define	COLOR_LEVEL_BACKGROUND GFX_COLOR(32, 32, 32)
	Background color for tank level indicator.
#define	COLOR_DEMAND_NORMAL GFX_COLOR(64, 192, 64)
	Normal fill color for demand indicator.
#define	COLOR_DEMAND_CRITICAL GFX_COLOR(192, 64, 64)
	Critical fill color for demand indicator.
#define	COLOR_DEMAND_BACKGROUND GFX_COLOR(32, 32, 32)
	Background color for demand indicator.
Maximum and initial values of process parameters

#define	VALUE_LEVEL_MAXIMUM 127
	Maximum level of tank.
#define	VALUE_LEVEL_INITIAL 0
	Initial level of tank.
#define	VALUE_SUPPLY_MAXIMUM VALUE_LEVEL_MAXIMUM
	Maximum value of supply.
#define	VALUE_SUPPLY_INITIAL (VALUE_SUPPLY_MAXIMUM / 2)
	Initial value of supply.
#define	VALUE_DEMAND_MAXIMUM VALUE_LEVEL_MAXIMUM
	Maximum value of demand.
#define	VALUE_DEMAND_INITIAL 0
	Initial value of demand.
Widget sizes and positions

#define	WIDGET_LEVEL_SIZE_X 52
	Height of progress bar for tank level.
#define	WIDGET_LEVEL_SIZE_Y 121
	Width of progress bar for tank level.
#define	WIDGET_LEVEL_POSITION_X 134
	X coordinate of progress bar for tank level.
#define	WIDGET_LEVEL_POSITION_Y 59
	Y coordinate of progress bar for tank level.
#define	WIDGET_SUPPLY_SIZE_X 37
	Height of slider for supply.
#define	WIDGET_SUPPLY_SIZE_Y 105
	Width of slider for supply.
#define	WIDGET_SUPPLY_POSITION_X 39
	X coordinate of slider for supply.
#define	WIDGET_SUPPLY_POSITION_Y 85
	Y coordinate of slider for supply.
#define	WIDGET_DEMAND_SIZE_X 20
	Height of progress bar for demand indication.
#define	WIDGET_DEMAND_SIZE_Y 45
	Width of progress bar for demand indication.
#define	WIDGET_DEMAND_POSITION_X 250
	X coordinate of progress bar for demand indication.
#define	WIDGET_DEMAND_POSITION_Y 100
	Y coordinator of progress bar for demand indication.
Bitmap filenames, sizes and positions

#define	BITMAP_BACKGROUND_FILENAME "p_tankbg"
	Filename of background bitmap.
#define	BITMAP_BACKGROUND_SIZE_X 320
	Width of background bitmap.
#define	BITMAP_BACKGROUND_SIZE_Y 240
	Height of background bitmap.
#define	BITMAP_BACKGROUND_POSITION_X 0
	X coordinate of background bitmap.
#define	BITMAP_BACKGROUND_POSITION_Y 0
	Y coordinate of background bitmap.
#define	BITMAP_RED_LIGHT_FILENAME "p_lgtred"
	Filename of red alarm light bitmap.
#define	BITMAP_GREEN_LIGHT_FILENAME "p_lgtgrn"
	Filename of green alarm light bitmap.
#define	BITMAP_LIGHT_SIZE_X 38
	Width of alarm light bitmap.
#define	BITMAP_LIGHT_SIZE_Y 38
	Height of alarm light bitmap.
#define	BITMAP_LIGHT_POSITION_X 241
	X coordinate of alarm light bitmap.
#define	BITMAP_LIGHT_POSITION_Y 26
	Y coordinate of alarm light bitmap.
Application timing configuration

#define	TICK_RATE 30
	Application tick rate.
#define	TICKS_PER_RANDOM_UPDATE 9
	Application ticks between each update of random variable.

Detailed Description

The water tank application is a process control-inspired demonstration of the slider, progress bar and command button widgets in the Widget toolkit; bitmaps of the Graphics display system; and basic use of the Window toolkit.

The application consists of a slider for controlling the supply (flow in) of water to a tank, and two progress bars for indicating the level of the water tank and the time-varying demand (flow out) for water, respectively. An alarm light changes color from green to red whenever the tank overflows, and the indicator for demand changes color if the demand exceeds the supply and available water in the tank.

This application makes use of the Timer driver for maintaining a constant update rate regardless of the workqueue load. The Fileloader utility is used to load the alarm light bitmaps to hugemem, allowing for synchronous drawing of them.

Simulated process

The process in this application was created simply to get a time-varying system, and is not meant to represent a real-world one. This section explains how the process is computed.

At iteration n, the process parameters are:

r(n) : random value
d(n) : demand
l(n) : level of tank
f(n) : total flow of the system
s(n) : supply

First, the random value is computed by use of the logistic map with scaling:

r(n) = q * (r(n-1) * (k - r(n-1))) / k

If r(0) is in the range [1 , k - 1], this function will return a value in the same range. The factor q affects how chaotic the logistic function behaves: For values close to the upper bound of 4, the function will seem quite random. In the implementation, q has been set to 3.95 and is represented by the ratio 79 / 20 since integer multiplications must be used. The maximum value k is set to the same as the maximum level of the tank: 127.

The demand is then computed from a weighted mean:

d(n) = (2 * d(n-1) + l(n-1) + r(n)) / 4

Disregarding the random component, this will essentially give a low-pass filtered response to changes in demand and tank level.

The flow of the system is then computed as:

f(n) = (s(n) - d(n)) / t

The factor t can be used to "time-stretch" the simulated process, and has been set to 4 in the implementation. The maximum value of supply is the same as the maximum level of the tank: 127.

Finally, the level of the tank is then computed as:

l(n) = l(n-1) + f(n)

However, the level of the tank is bounded by 0 and its maximum value. If the tank's level reaches 0, the demand indicator will change color to indicate that the supply is insufficient. If it reaches the maximum, the overflow alarm light will change color to indicate that the supply is too great. As stated above, the maximum level of the tank is set to 127.

Define Documentation

#define BITMAP_BACKGROUND_FILENAME "p_tankbg"

Filename of background bitmap.

Definition at line 145 of file app_tank.c.

Referenced by tank_loader().

#define BITMAP_BACKGROUND_POSITION_X 0

X coordinate of background bitmap.

Definition at line 151 of file app_tank.c.

Referenced by tank_loader().

#define BITMAP_BACKGROUND_POSITION_Y 0

Y coordinate of background bitmap.

Definition at line 153 of file app_tank.c.

Referenced by tank_loader().

#define BITMAP_BACKGROUND_SIZE_X 320

Width of background bitmap.

Definition at line 147 of file app_tank.c.

Referenced by tank_loader().

#define BITMAP_BACKGROUND_SIZE_Y 240

Height of background bitmap.

Definition at line 149 of file app_tank.c.

Referenced by tank_loader().

#define BITMAP_GREEN_LIGHT_FILENAME "p_lgtgrn"

Filename of green alarm light bitmap.

Definition at line 158 of file app_tank.c.

Referenced by tank_loader().

#define BITMAP_LIGHT_POSITION_X 241

X coordinate of alarm light bitmap.

Definition at line 164 of file app_tank.c.

Referenced by tank_worker().

#define BITMAP_LIGHT_POSITION_Y 26

Y coordinate of alarm light bitmap.

Definition at line 166 of file app_tank.c.

Referenced by tank_worker().

#define BITMAP_LIGHT_SIZE_X 38

Width of alarm light bitmap.

Definition at line 160 of file app_tank.c.

Referenced by app_tank_launch(), and tank_worker().

#define BITMAP_LIGHT_SIZE_Y 38

Height of alarm light bitmap.

Definition at line 162 of file app_tank.c.

Referenced by app_tank_launch(), and tank_worker().

#define BITMAP_RED_LIGHT_FILENAME "p_lgtred"

Filename of red alarm light bitmap.

Definition at line 156 of file app_tank.c.

Referenced by tank_loader().

#define COLOR_DEMAND_BACKGROUND GFX_COLOR(32, 32, 32)

Background color for demand indicator.

Definition at line 78 of file app_tank.c.

Referenced by app_tank_launch(), and tank_worker().

#define COLOR_DEMAND_CRITICAL GFX_COLOR(192, 64, 64)

Critical fill color for demand indicator.

Definition at line 76 of file app_tank.c.

Referenced by tank_worker().

#define COLOR_DEMAND_NORMAL GFX_COLOR(64, 192, 64)

Normal fill color for demand indicator.

Definition at line 74 of file app_tank.c.

Referenced by app_tank_launch(), and tank_worker().

#define COLOR_LEVEL_BACKGROUND GFX_COLOR(32, 32, 32)

Background color for tank level indicator.

Definition at line 72 of file app_tank.c.

BITMAP_RED_LIGHT	ID and index of bitmap for red alarm light.
BITMAP_GREEN_LIGHT	ID and index of bitmap for green alarm light.
NR_OF_BITMAPS	Total number of bitmaps loaded to hugemem.

CMD_NONE	Command event value to use for supply-slider.
CMD_EXIT	Command event value to use for exit-button.

LOAD_RED_LIGHT	Red alarm light bitmap will be loaded to hugemem.
LOAD_GREEN_LIGHT	Green alarm light bitmap will be loaded to hugemem.
LOAD_BACKGROUND	Background bitmap will be shown.
LOAD_FINISHED	The application's widgets will be shown, and its timer started.

static bool tank_frame_handler	(	struct wtk_basic_frame *	basic_frame,
		win_command_t	command_data
	)			`[static]`

	basic_frame	Pointer to the application frame.
	command_data	Data for the command event.

Water tank application [Applications]

Data Structures

Enumerations

Functions

Variables

Color scheme

Maximum and initial values of process parameters

Widget sizes and positions

Bitmap filenames, sizes and positions

Application timing configuration

Detailed Description

Define Documentation

Enumeration Type Documentation

Function Documentation

Variable Documentation

Water tank application
[Applications]