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Working end of screen scrolling

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This commit is contained in:
Daniele Verducci su MatissePenguin 2021-02-22 19:55:53 +01:00
parent 2c65665900
commit 2b3f9946d9
3 changed files with 59 additions and 88 deletions
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105
pat80-io-devices/composite-pal-adapter/software/avr-assembly/character_generator.asm
View File

@ -17,10 +17,6 @@ draw_char:
; But all the fonts are 1 byte large, so a glyph is 1*height bytes:
; glyph_pointer = FONT + (ascii_code * FONT_HEIGHT)
; Save current chunk cursor position (Y)
mov r2, YL
mov r3, YH
; Load first glyph position on Z
ldi ZH, high(FONT<<1)
ldi ZL, low(FONT<<1)
@ -31,6 +27,8 @@ draw_char:
add ZL, r0
adc ZH, r1
; Z contain our glyph's first byte position: draw it
; Obtain drawing position in framebuffer memory (in Y)
call update_mem_pointer
; The drawing consist of FONT_HEIGHT cycles. Every glyph byte is placed on its own line
; on screen. To do this, we place it LINE_COLUMNS bytes after the previous one.
ldi HIGH_ACCUM, FONT_HEIGHT
@ -49,22 +47,17 @@ draw_char:
inc POS_COLUMN
; Check if end of line
cpi POS_COLUMN, LINE_COLUMNS
breq draw_char_eol
; Reset chunk position to first glyph line of next column
mov YL, r2 ; first restore Y
mov YH, r3
adiw YH:YL,1 ; just increment pre-char-drawing-saved chunk cursor position by 1
brsh draw_char_eol
ret
draw_char_eol:
; end of line
adiw YH:YL,1 ; increment chunk cursor position by 1 (begin of next line on screen)
clr POS_COLUMN ; reset column to 0
; check if reached end of screen
cpi POS_ROWP, SCREEN_HEIGHT-FONT_HEIGHT
breq draw_char_eos
; if not end of screen, increment row
; Move cursor to next line
ldi HIGH_ACCUM, FONT_HEIGHT
add POS_ROWP, HIGH_ACCUM
; check if reached end of screen
cpi POS_ROWP, SCREEN_HEIGHT
brsh draw_char_eos
ret
draw_char_eos:
; end of screen: scroll screen but leave line pointer to last line
@ -76,60 +69,28 @@ cursor_pos_home:
; Set all positions to 0
clr POS_COLUMN
clr POS_ROWP
; Load framebuffer start position to Y
ldi YH, high(FRAMEBUFFER)
ldi YL, low(FRAMEBUFFER)
ret
; Updates framebuffer pointer (Y) to point to current text cursor position (POS_COLUMN, POS_ROWP)
; Usage:
; ldi POS_COLUMN, 10
; ldi POS_ROWP, 13
; call set_framebuffer_pointer_to_text_cursor
; @modifies Y, R0, R1
; set_framebuffer_pointer_to_text_cursor:
; ; Load framebuffer start position to Y
; ldi YH, high(FRAMEBUFFER)
; ldi YL, low(FRAMEBUFFER)
; ; Obtain offset between 0,0 and current cursor position
; mul POS_COLUMN, POS_ROWP ; result is in r1,r0 ; NOTE: wrong, multiplicate with bytes per row
; ; Sum offset to Y
; add YL, r0
; adc YH, r1
; ret
; Draws a newline
; Moves cursor to start of following screen line
; Takes care of particular cases, i.e. end of screen (shifts all screen up by one line)
draw_carriage_return:
; Check if end of screen
cpi POS_ROWP, SCREEN_HEIGHT
brne draw_carriage_return_not_eos
call scroll_screen
dec POS_ROWP ; compensate for next inc
draw_carriage_return_not_eos:
; Move cursor to line start
ldi POS_COLUMN, 0
; Move cursor to next line
ldi HIGH_ACCUM, FONT_HEIGHT
add POS_ROWP, HIGH_ACCUM
; Compute memory pointer offset
mul POS_COLUMN, POS_ROWP ; result overwrites r0 and r1!
; Set pointer to start of framebuffer
ldi ZL, low(FRAMEBUFFER)
ldi ZH, high(FRAMEBUFFER)
; Add offset to pointer
add ZL, r0
adc ZH, r1
ret
; draw_carriage_return:
; ; Move cursor to line start
; ldi POS_COLUMN, 0
; ; Move cursor to next line
; ldi HIGH_ACCUM, FONT_HEIGHT
; add POS_ROWP, HIGH_ACCUM
; ; Check if end of screen
; cpi POS_ROWP, SCREEN_HEIGHT
; brsh draw_carriage_return_eos
; ret
; draw_carriage_return_eos:
; call scroll_screen
; Scrolls the screen by one line (=LINE_COLUMNS*FONT_HEIGHT bytes)
; and clears the last line (FRAMEBUFFER_END - LINE_COLUMNS*FONT_HEIGHT bytes)
; @uses A, Z
scroll_screen:
clr POS_COLUMN ; cursor to first column
; "Read" Pointer to first char of second line
ldi YH, high(FRAMEBUFFER+(LINE_COLUMNS*FONT_HEIGHT))
ldi YL, low(FRAMEBUFFER+(LINE_COLUMNS*FONT_HEIGHT))
@ -140,9 +101,9 @@ scroll_screen:
scroll_screen_copy_loop:
ld A, Y+
st Z+, A
cpi ZH, high(FRAMEBUFFER_END-(LINE_COLUMNS*FONT_HEIGHT))
cpi YH, high(FRAMEBUFFER_END)
brne scroll_screen_copy_loop
cpi ZL, low(FRAMEBUFFER_END-(LINE_COLUMNS*FONT_HEIGHT))
cpi YL, low(FRAMEBUFFER_END)
brne scroll_screen_copy_loop
; All the lines have been "shifted" up by one line.
; The first line is lost and the last is duplicate. Clear the last.
@ -153,8 +114,26 @@ scroll_screen:
brne scroll_screen_clear_loop
cpi r30, low(FRAMEBUFFER_END)
brne scroll_screen_clear_loop
; Last line cleared. Leave cursor pointer to last line start
ldi YH, high(FRAMEBUFFER_END-LINE_COLUMNS*FONT_HEIGHT)
ldi YL, low(FRAMEBUFFER_END-LINE_COLUMNS*FONT_HEIGHT)
; Last line cleared. Set cursor position
clr POS_COLUMN ; cursor to first column
ldi POS_ROWP, SCREEN_HEIGHT-FONT_HEIGHT
ret
; Sets the Y register to point to the cursor's first line memory position
; The cursor's position is represented by registers POS_COLUMN and POS_ROWP
update_mem_pointer:
; Compute memory pointer offset: offset = (LINE_COLUMNS*POS_ROWP)+POS_COLUMN
; LINE_COLUMNS*POS_ROWP
ldi HIGH_ACCUM, LINE_COLUMNS
mul HIGH_ACCUM, POS_ROWP ; result overwrites r0 and r1!
; ...+POS_COLUMN
add r0, POS_COLUMN
clr HIGH_ACCUM
adc r0, HIGH_ACCUM
; Set pointer to start of framebuffer
ldi YL, low(FRAMEBUFFER)
ldi YH, high(FRAMEBUFFER)
; Add offset to pointer
add YL, r0
adc YH, r1
ret

1
pat80-io-devices/composite-pal-adapter/software/avr-assembly/example_data/cat.asm
View File

@ -11,7 +11,6 @@ draw_cat:
; wait
ser r19
cat_wait_loop_1:
ldi r20, 32
dec r19
brne cat_wait_loop_1
; if reached the last framebuffer byte, exit cycle

41
pat80-io-devices/composite-pal-adapter/software/avr-assembly/main.asm
View File

@ -79,17 +79,17 @@ main:
; clear ram
;*** Load data into ram ***
; Set X to 0x0100
; ldi XH, high(FRAMEBUFFER)
; ldi XL, low(FRAMEBUFFER)
; load_mem_loop:
; clr r17
; st X+, r17
; ; if reached the last framebuffer byte, exit cycle
; cpi XH, 0b00111110
; brne load_mem_loop ; if not 0, repeat h_picture_loop
; cpi XL, 0b11000000
; brne load_mem_loop ; if not 0, repeat h_picture_loop
Set X to 0x0100
ldi XH, high(FRAMEBUFFER)
ldi XL, low(FRAMEBUFFER)
load_mem_loop:
clr r17
st X+, r17
; if reached the last framebuffer byte, exit cycle
cpi XH, 0b00111110
brne load_mem_loop ; if not 0, repeat h_picture_loop
cpi XL, 0b11000000
brne load_mem_loop ; if not 0, repeat h_picture_loop
@ -122,34 +122,27 @@ main:
; draw example image
call draw_cat
;call draw_cat
; test draw character routine
call draw_carriage_return
call draw_carriage_return
call draw_carriage_return
call cursor_pos_home
ldi r18, 0x41
dctest:
ldi r18, 0x41
draw_chars:
mov HIGH_ACCUM, r18
call draw_char
inc r18
cpi r18, 0x5B
brne dc_continue
ldi r18, 0x41
call draw_carriage_return
dc_continue:
; wait
ser r19
dc_wait_loop_1:
ser r20
ldi r24, 64
dc_wait_loop_2:
dec r20
dec r24
brne dc_wait_loop_2
dec r19
brne dc_wait_loop_1
inc r18
cpi r18, 0x5B
brne draw_chars
jmp dctest