xen32os/xenrom/logo.asm
2024-02-07 19:33:35 +01:00

184 lines
3.0 KiB
NASM

show_logo:
icl ; disable interrupts
; Save old interrupt handler
mov r0, [0x3fc]
push r0
; Set vsync interrupt handler to logo display
mov [0x3fc], intr_vsync_logo
mov [SHOWING_LOGO], 1
mov [FRAMENR], 0
ise ; Enable interrupts
; Wait for logo display interrupt to return
show_logo_wait:
cmp [SHOWING_LOGO], 1
ifz jmp show_logo_wait
icl ; Restore interrupt handler
pop r0
mov [0x3fc], r0
; Draw logo in black (clear)
mov r0, 0
mov r1, 0
call draw_logo
ret
cycle_data: #include_bin "data/logo_cycle.dat"
; defines LOGO_LENGTH
#include "data/logo_cycle.inc"
intr_vsync_logo:
; [rsp] = interrupt number
; [rsp+4] = flags
; [rsp+8] = previous instuction
inc [FRAMENR]
mov r2, [FRAMENR]
cmp r2, LOGO_LENGTH
ifgteq mov [SHOWING_LOGO], 0
; fetch brightness and glitchiness
mul r2, 2
add r2, cycle_data
movz.8 r0, [r2]
inc r2
movz.8 r1, [r2]
call draw_logo
add rsp, 4 ; pop interrupt number
reti
boot_logo: #include_bin "data/logo.dat"
; defines LOGO_WIDTH, LOGO_HEIGHT:
#include "data/logo.inc"
const LOGO_SCALE: 8 ; pixels per pixel in logo
; input: r0: 0-255 color multiplier
; input: r1: glitch effect
draw_logo:
mov r31, r0
mov r30, r1
; r0: x counter
; r1: y counter
; r2: pointer to current boot logo index
; r5: x on screen start
; r6: y on screen start
mov r5, SCREEN_WIDTH
mov r6, LOGO_WIDTH
mul r6, LOGO_SCALE
sub r5, r6
ror r5, 1
mov r6, SCREEN_HEIGHT
mov r7, LOGO_HEIGHT
mul r7, LOGO_SCALE
sub r6, r7
ror r6, 1
mov r2, boot_logo
mov r1, 0
draw_loop_y:
cmp r1, LOGO_HEIGHT
ifz jmp draw_logo_done
mov r0, 0
draw_loop_x:
cmp r0, LOGO_WIDTH
ifz jmp draw_loop_x_done
; r3: color to draw
mov r3, 0x00000000 ; black
xor r2, r30
cmp.8 [r2], 1
ifz mov r3, 0x00040401 ; blue
cmp.8 [r2], 2
ifz mov r3, 0x00040403; white
cmp.8 [r2], 3
ifz mov r3, 0x00010204; orange
xor r2, r30
cmp r30, 0
ifz jmp no_color_glitch
cmp r3, 0
ifnz xor r3, r0
ifnz xor r3, r1
no_color_glitch:
mov r28, r31
srl r28, 2
mul r3, r28 ; brightness
xor r3, r29
or r3, 0xff000000
; r4: screen buffer index of top left
mov r4, r6
mov r7, r1
mul r7, LOGO_SCALE
add r4, r7
mul r4, 640
add r4, r5
mov r7, r0
mul r7, LOGO_SCALE
add r4, r7
mul r4, 4
add r4, BG_FRAMEBUFFER
; r7: paint x
; r8: point y
mov r7, 0
draw_loop_px:
cmp r7, LOGO_SCALE
ifz jmp draw_loop_px_done
mov r8, 0
draw_loop_py:
cmp r8, LOGO_SCALE
ifz jmp draw_loop_py_done
mov r9, r8
mul r9, 640
add r9, r7
mul r9, 4
add r9, r4
mov [r9], r3
inc r8
jmp draw_loop_py
draw_loop_py_done:
inc r7
jmp draw_loop_px
draw_loop_px_done:
inc r2
inc r0
jmp draw_loop_x
draw_loop_x_done:
inc r1
jmp draw_loop_y
draw_logo_done:
ret