Color Palette
10 Points
memory
Instructions
Your friend José is a teacher in a local school. He had an idea for some fun experiments to show how colors can be combined to produce different ones.
He asked for your help with those experiments.
Note
A color is represented in this exercise by a 32-bit (4-byte) number, encoding its RGB value.
A RGB value consists of 3 channels, Red, Green and Blue, each one occupying 8 bits (1 byte).
The fourth byte is usually reserved for the Alpha channel, but in this exercise its value will be empty (0).
1. Get the RGB value for a color
The values for each color are already stored in a table, defined in another source file. A color is identified by an unique address in this table.
Define a function get_color_value that returns the 32-bit value for a color.
This function takes as parameter a valid address for this color in the color table.
get_color_value(black)
// => 0Hint - 32 bits are equivalent to 4 bytes.
2. Add base color
In order to mix different colors, José will first fix a base one and change only the secondary color being combined with it.
Define a function add_base_color that saves the 32-bit value for a color in the variable base_color, so it can be used later.
This function has no return value and takes as parameter the address of the color in the color table.
The variable base_color is defined by you and must be accessible from other source files.
There will be no more than 1 base color at the same time. If a new base color is added, the old one is discarded.
By default, at the start of the program, base_color should be initialized with the 32-bit value for white, which is 0xFFFFFF00.
Hint - NASM accepts numbers defined in hexadecimal using 0x at the start, such as in 0xFFFFFF00.
3. Define constants for primary colors
José expects to make many combinations using primary colors, so he wants to have them separated for fast access.
Since he is using RGB to represent colors, the primary colors are:
RED, with the value0xFF000000.GREEN, with the value0x00FF0000.BLUE, with the value0x0000FF00.
Define one constant for each of those colors. Those constants must be accessible from other source files.
4. Combine colors
The colors should be combined according to a combining_function defined in another source file.
This function takes as parameters the 32-bit values for base_color and for a secondary color to be mixed with it.
It returns the 32-bit value for the combined color.
Define a function make_color_combination that combines two colors and saves the result in memory.
This function has no return value and takes as parameters, in this order:
- The address where the 32-bit value for the combined color should be stored.
- The address of a secondary color in the color table, to be combined with the primary color.
Caution
Notice that combining_function may modify the values in registers you are using.
Make sure to save any variable you need in memory before calling the function.
Color Palette
10 Points
memory
Instructions
Your friend José is a teacher in a local school. He had an idea for some fun experiments to show how colors can be combined to produce different ones.
He asked for your help with those experiments.
Note
A color is represented in this exercise by a 32-bit (4-byte) number, encoding its RGB value.
A RGB value consists of 3 channels, Red, Green and Blue, each one occupying 8 bits (1 byte).
The fourth byte is usually reserved for the Alpha channel, but in this exercise its value will be empty (0).
1. Get the RGB value for a color
The values for each color are already stored in a table, defined in another source file. A color is identified by an unique address in this table.
Define a function get_color_value that returns the 32-bit value for a color.
This function takes as parameter a valid address for this color in the color table.
get_color_value(black)
// => 0Hint - 32 bits are equivalent to 4 bytes.
2. Add base color
In order to mix different colors, José will first fix a base one and change only the secondary color being combined with it.
Define a function add_base_color that saves the 32-bit value for a color in the variable base_color, so it can be used later.
This function has no return value and takes as parameter the address of the color in the color table.
The variable base_color is defined by you and must be accessible from other source files.
There will be no more than 1 base color at the same time. If a new base color is added, the old one is discarded.
By default, at the start of the program, base_color should be initialized with the 32-bit value for white, which is 0xFFFFFF00.
Hint - NASM accepts numbers defined in hexadecimal using 0x at the start, such as in 0xFFFFFF00.
3. Define constants for primary colors
José expects to make many combinations using primary colors, so he wants to have them separated for fast access.
Since he is using RGB to represent colors, the primary colors are:
RED, with the value0xFF000000.GREEN, with the value0x00FF0000.BLUE, with the value0x0000FF00.
Define one constant for each of those colors. Those constants must be accessible from other source files.
4. Combine colors
The colors should be combined according to a combining_function defined in another source file.
This function takes as parameters the 32-bit values for base_color and for a secondary color to be mixed with it.
It returns the 32-bit value for the combined color.
Define a function make_color_combination that combines two colors and saves the result in memory.
This function has no return value and takes as parameters, in this order:
- The address where the 32-bit value for the combined color should be stored.
- The address of a secondary color in the color table, to be combined with the primary color.
Caution
Notice that combining_function may modify the values in registers you are using.
Make sure to save any variable you need in memory before calling the function.