; Parva CPU version 0.1
; Parva GPU version 0.1 on IO port 0x1

nop
b _start

string:
.data 1 2 3 3 4 8 5 4 6 3 7 0

characters:
; upper 24 pixels, lower 24 pixels, width
char_null: ; 0
.data 0
characters_plus_1:
.data 0
characters_plus_2:
.data 0
char_H: ; 1
.data 0b000000_100010_100010_111110 0b100010_100010_100010_000000 6
char_e: ; 2
.data 0b000000_000000_011000_100100 0b111100_100000_011100_000000 5
char_l: ; 3
.data 0b000000_100000_100000_100000 0b100000_100000_010000_000000 3
char_o: ; 4
.data 0b000000_000000_011000_100100 0b100100_100100_011000_000000 5
char_w: ; 5
.data 0b000000_000000_101010_101010 0b101010_101010_010100_000000 6
char_r: ; 6
.data 0b000000_000000_011000_100000 0b100000_100000_100000_000000 4
char_d: ; 7
.data 0b000000_000100_011100_100100 0b100100_100100_011100_000000 5
char_space: ; 8
.data 0 0 4

_start:

sw x0, 0b01_0100_000000(upper) ; gpu clear screen
li x6, 1 ; x position
li x7, 1 ; y position
li x0, string
loop:
sd x67, 0b01_0000_000000(upper) ; gpu move cursor
lw x1, 0(x0) ; x1 = current character
beqz x1, end
add x2, x1, x1
add x1, x2, x1 ; x1 *= 3
lw x2, characters(x1) ; upper 24 pixels
lw x3, characters_plus_1(x1) ; lower 24 pixels
sd x01, 0b01_0011_000000(upper) ; gpu print buffer to screen
sd x23, 0b01_0010_000000(upper) ; gpu print 6x8 char
lw x4, characters_plus_2(x1) ; width
add x6, x6, x4 ; x position += width
addi x0, x0, 1
b loop

end:

sd x01, 0b01_0011_000000(upper) ; gpu print buffer to screen
wfi