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