risc-v

.eqv BMP_FILE_SIZE 230456
.eqv BYTES_PER_ROW 960

	.data
#space for the 320x240px 24-bits bmp image
.align 4
res:	.space 2
image:	.space BMP_FILE_SIZE
oname: .asciz "final2.bmp"
fname:	.asciz "racoon.bmp"
prompt1: .asciz "Give x0 and x1 coordinates (starting and ending in x-axis)\n"
bonus: .asciz "x1: \n"
prompt2: .asciz  "Give y0 and y1 coordinates (starting and ending in y-axis)\n"
bonus1: .asciz "y1: \n"
prompt3: .asciz "Give treshold value for the conversion\n"

	.text
main:

	jal	read_bmp
	jal 	get_inputs
	#li t6, 50
	#li s9, 50
	#li a3, 200
	#li a4, 200
	#li s11, 30
	li s7,100
	mul s11,s11,s7
	addi s9,s9,-1

	
	loop1:
	mv s10,t6
	addi s9,s9,1
	bgt s9,a3, save
	j loop2	

	loop2:
	mv a0, s10
	mv a1, s9
	jal get_pixel
	mv s8,a0
	mv a0,s10
	bgt s8,s11 change_color_W
	ble s8,s11 change_color_B
	back:
	addi s10, s10,1
	bgt s10,a4, loop1
	j loop2
	
save:
	jal	save_bmp

exit:	li 	a7,10		#Terminate the program
	ecall

# ============================================================================
change_color_B:
	li a2, 0x00000000 	#color - 00RRGGBB
	jal    put_pixel
	j back

change_color_W:
	li a2, 0x00FFFFFF	#color - 00RRGGBB
	jal    put_pixel
	j back
	
read_bmp:
#description: 
#	reads the contents of a bmp file into memory
#arguments:
#	none
#return value: none
	addi sp, sp, -4		#push $s1
	sw s1, 0(sp)
#open file
	li a7, 1024
        la a0, fname		#file name 
        li a1, 0		#flags: 0-read file
        ecall
	mv s1, a0      # save the file descriptor
	
#check for errors - if the file was opened
#...

#read file
	li a7, 63
	mv a0, s1
	la a1, image
	li a2, BMP_FILE_SIZE
	ecall

#close file
	li a7, 57
	mv a0, s1
        ecall
	
	lw s1, 0(sp)		#restore (pop) s1
	addi sp, sp, 4
	jr ra

# ============================================================================
save_bmp:
#description: 
#	saves bmp file stored in memory to a file
#arguments:
#	none
#return value: none
	addi sp, sp, -4		#push s1
	sw s1, (sp)
#open file
	li a7, 1024
        la a0, oname		#file name 
        li a1, 1		#flags: 1-write file
        ecall
	mv s1, a0      # save the file descriptor
	
#check for errors - if the file was opened
#...

#save file
	li a7, 64
	mv a0, s1
	la a1, image
	li a2, BMP_FILE_SIZE
	ecall

#close file
	li a7, 57
	mv a0, s1
        ecall
	
	lw s1, (sp)		#restore (pop) $s1
	addi sp, sp, 4
	jr ra


# ============================================================================
put_pixel:
#description: 
#	sets the color of specified pixel
#arguments:
#	a0 - x coordinate
#	a1 - y coordinate - (0,0) - bottom left corner
#	a2 - 0RGB - pixel color
#return value: none

	la t1, image	#adress of file offset to pixel array
	addi t1,t1,10
	lw t2, (t1)		#file offset to pixel array in $t2
	la t1, image		#adress of bitmap
	add t2, t1, t2	#adress of pixel array in $t2
	
	#pixel address calculation
	li t4,BYTES_PER_ROW
	mul t1, a1, t4 #t1= y*BYTES_PER_ROW
	mv t3, a0		
	slli a0, a0, 1
	add t3, t3, a0	#$t3= 3*x
	add t1, t1, t3	#$t1 = 3x + y*BYTES_PER_ROW
	add t2, t2, t1	#pixel address 
	
	#set new color
	sb a2,(t2)		#store B
	srli a2,a2,8
	sb a2,1(t2)		#store G
	srli a2,a2,8
	sb a2,2(t2)		#store R

	jr ra
# ============================================================================
get_pixel:
#description: 
#	returns color of specified pixel
#arguments:
#	a0 - x coordinate
#	a1 - y coordinate - (0,0) - bottom left corner
#return value:
#	a0 - 0RGB - pixel color

	la t1, image		#adress of file offset to pixel array
	addi t1,t1,10
	lw t2, (t1)		#file offset to pixel array in $t2
	la t1, image		#adress of bitmap
	add t2, t1, t2		#adress of pixel array in $t2
	
	#pixel address calculation
	li t4,BYTES_PER_ROW
	mul t1, a1, t4 		#t1= y*BYTES_PER_ROW
	mv t3, a0		
	slli a0, a0, 1
	add t3, t3, a0		#$t3= 3*x
	add t1, t1, t3		#$t1 = 3x + y*BYTES_PER_ROW
	add t2, t2, t1	#pixel address 
	
	#get color
	lbu a0,(t2)		#load B
	mv s2, a0
	lbu t1,1(t2)		#load G
	#slli t1,t1,8
	mv s3, t1
	#or a0, a0, t1
	lbu t1,2(t2)		#load R
        #slli t1,t1,16
        mv s4, t1
	#or a0, a0, t1
	li s6, 7
	mul s2,s2,s6
	li s6,72
	mul s3,s3,s6
	li s6, 21
	mul s4,s4,s6
	add s2,s2,s3
	add,s2,s2,s4
	mv a0,s2				
	jr ra


# ============================================================================
get_inputs:

#reading the x values
	li a7, 4 
	la a0, prompt1
	ecall
	li a7, 5 
	ecall
	mv t6, a0
	li a7, 4 
	la a0, bonus
	ecall
	li a7, 5
	ecall
	mv a4,a0
#reading the y values


	li a7, 4 
	la a0, prompt2
	ecall
	li a7, 5 
	ecall
	mv s9, a0
	li a7, 4 
	la a0, bonus1
	ecall
	li a7, 5
	ecall
	mv a3, a0
#reading treshold value

	li a7, 4 
	la a0, prompt3
	ecall
	li a7, 5 
	ecall
	mv s11,a0
	jr ra