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Untested code

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This commit is contained in:
Daniele Verducci (ZenPenguin)
2021-02-22 13:59:55 +01:00
parent 75f5ce057f
commit 2c65665900
3 changed files with 35 additions and 34 deletions
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65
pat80-io-devices/composite-pal-adapter/software/avr-assembly/character_generator.asm
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@@ -76,7 +76,6 @@ cursor_pos_home:
; Set all positions to 0
clr POS_COLUMN
clr POS_ROWP
clr POS_FINE
; Load framebuffer start position to Y
ldi YH, high(FRAMEBUFFER)
ldi YL, low(FRAMEBUFFER)
@@ -88,16 +87,16 @@ cursor_pos_home:
; 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
; Sum offset to Y
add YL, r0
adc YH, r1
ret
; 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
@@ -105,19 +104,25 @@ set_framebuffer_pointer_to_text_cursor:
; 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:
; Set memory pointer to start of line
sub YL, POS_COLUMN
sbci YH, 0
; Set cursor to start of current line
clr POS_COLUMN
; Go to next line
ldi HIGH_ACCUM, high(LINE_COLUMNS*FONT_HEIGHT)
add YH, HIGH_ACCUM
ldi HIGH_ACCUM, low(LINE_COLUMNS*FONT_HEIGHT)
adc YL, HIGH_ACCUM
; Update row pointer
ldi HIGH_ACCUM, FONT_HEIGHT
add POS_ROWP, HIGH_ACCUM
; 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
; Scrolls the screen by one line (=LINE_COLUMNS*FONT_HEIGHT bytes)
@@ -126,18 +131,18 @@ draw_carriage_return:
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)
ldi YH, high(FRAMEBUFFER+(LINE_COLUMNS*FONT_HEIGHT))
ldi YL, low(FRAMEBUFFER+(LINE_COLUMNS*FONT_HEIGHT))
; "Write" Pointer to first char of first line
ldi XH, high(FRAMEBUFFER)
ldi XL, low(FRAMEBUFFER)
ldi ZH, high(FRAMEBUFFER)
ldi ZL, low(FRAMEBUFFER)
; Copy data
scroll_screen_copy_loop:
ld A, Y+
st Z+, A
cpi r31, high(FRAMEBUFFER_END-LINE_COLUMNS*FONT_HEIGHT)
cpi ZH, high(FRAMEBUFFER_END-(LINE_COLUMNS*FONT_HEIGHT))
brne scroll_screen_copy_loop
cpi r30, low(FRAMEBUFFER_END-LINE_COLUMNS*FONT_HEIGHT)
cpi ZL, low(FRAMEBUFFER_END-(LINE_COLUMNS*FONT_HEIGHT))
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.