First working text mode without end of screen scroll
This commit is contained in:
Daniele Verducci su MatissePenguin
parent
9d6e6efd13
commit
467197fd23
@ -27,7 +27,7 @@ draw_char:
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; Obtain offset multiplying ascii_code * number_of_bytes_per_font
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ldi r17, FONT_HEIGHT
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mul HIGH_ACCUM, r17 ; result overwrites r0 and r1!
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; 16-bit addition between gliph's first byte position and offset (and store result in Z)
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; 16-bit addition between gliph's first byte position and offset (and store result in Z) to obtain our glyph position
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add ZL, r0
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adc ZH, r1
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; Z contain our glyph's first byte position: draw it
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@ -44,19 +44,66 @@ draw_char:
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; Decrement loop counter and exit if reached 0
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dec HIGH_ACCUM
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brne draw_char_loop
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; Char drawing is complete. Set chunk cursor position to next char first line
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; Char drawing is complete. Increment cursor position
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inc POS_COLUMN
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; Check if end of line
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cpi POS_COLUMN, 52
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breq draw_char_eol
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; Reset chunk position to first glyph line of next column
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mov YL, r2 ; first restore Y
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mov YH, r3
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adiw YH:YL,1 ; just increment pre-char-drawing-saved chunk cursor position by 1
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ret
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draw_char_eol:
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clr POS_COLUMN ; reset column to 0
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adiw YH:YL,1 ; increment chunk cursor position by 1 (begin of next line on screen)
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; Check if end of screen
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cpi YH, high(FRAMEBUFFER_END + 1)
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brne draw_char_end
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cpi YL, low(FRAMEBUFFER_END + 1)
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brne draw_char_end
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; End of screen reached! Scroll framebuffer by 1 line (=52*FONT_HEIGHT bytes)
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; TODO
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draw_char_end:
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ret
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; Sets the cursor to 0,0 and clears fine position
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cursor_pos_home:
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; Set Y to framebuffer start
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;ldi YH, high(FRAMEBUFFER)
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;ldi YL, low(FRAMEBUFFER)
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ldi YH, high(0x0068)
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ldi YL, low(0x0068)
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; Set all positions to 0
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clr POS_COLUMN
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clr POS_ROWP
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clr POS_FINE
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; Load framebuffer start position to Y
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ldi YH, high(FRAMEBUFFER)
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ldi YL, low(FRAMEBUFFER)
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; ldi YH, high(0x1000)
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; ldi YL, low(0x1000)
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ret
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; Updates framebuffer pointer (Y) to point to current text cursor position (POS_COLUMN, POS_ROWP)
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; Usage:
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; ldi POS_COLUMN, 55
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; ldi POS_ROWP, 13
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; call set_framebuffer_pointer_to_text_cursor ; (sets cursor to 4th character of second row in 13th row-pair = column 4, row 27 on screen)
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; @modifies Y, R0, R1
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set_framebuffer_pointer_to_text_cursor:
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; Load framebuffer start position to Y
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ldi YH, high(FRAMEBUFFER)
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ldi YL, low(FRAMEBUFFER)
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; Obtain offset between 0,0 and current cursor position
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mul POS_COLUMN, POS_ROWP ; result is in r1,r0
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; Sum offset to Y
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add YL, r0
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adc YH, r1
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ret
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; Draws a newline
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; Moves cursor to start of following screen line
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; Takes care of particular cases, i.e. end of screen (shifts all screen up by one line)
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draw_carriage_return:
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ret
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@ -29,9 +29,12 @@
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; *** reserved registers ***
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; Cursor Position
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.def POS_COLUMN = r21 ; absolute coarse position on line (0 to 51)
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.def POS_ROW = r20 ; absolute coarse position on line (0 to 51)
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.def POS_FINE = r24 ; fine position (bit inside coarse-position-pointed byte)
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; POS_COLUMN (0-103) represents the column on a pair of rows: 0 to 51 is the first row, 52 to 103 the second one
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; POS_ROWP (0-152) represent the pair of rows. POS_ROWP = 5 means the 10th and 11th rows
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; POS_FINE represents fine position (bit inside coarse-position-pointed chunk) in graphic mode.
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.def POS_COLUMN = r21
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.def POS_ROWP = r20
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.def POS_FINE = r24
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; Internal registers
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.def A = r0 ; accumulator
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.def STATUS = r25 ; signal status (see STATUS TABLE)
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@ -52,6 +55,7 @@
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; memory
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.equ FRAMEBUFFER = 0x0100
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.equ FRAMEBUFFER_END = 0x3EC0
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; start vector
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.org 0x0000
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@ -88,14 +92,54 @@ main:
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; test draw character routine
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call cursor_pos_home
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ldi r18, 0x30
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ldi r18, 0x21
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draw_chars:
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mov HIGH_ACCUM, r18
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call draw_char
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inc r18
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cpi r18, 0x64
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cpi r18, 0x7E
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brne draw_chars
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ldi r18, 0x21
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draw_chars2:
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mov HIGH_ACCUM, r18
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call draw_char
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inc r18
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cpi r18, 0x7E
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brne draw_chars2
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ldi r18, 0x21
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draw_chars3:
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mov HIGH_ACCUM, r18
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call draw_char
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inc r18
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cpi r18, 0x7E
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brne draw_chars3
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ldi r18, 0x21
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draw_chars4:
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mov HIGH_ACCUM, r18
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call draw_char
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inc r18
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cpi r18, 0x7E
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brne draw_chars4
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ldi r18, 0x21
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draw_chars5:
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mov HIGH_ACCUM, r18
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call draw_char
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inc r18
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cpi r18, 0x7E
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brne draw_chars5
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ldi r18, 0x21
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draw_chars6:
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mov HIGH_ACCUM, r18
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call draw_char
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inc r18
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cpi r18, 0x7E
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brne draw_chars6
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; *** timer setup (use 16-bit counter TC1) ***
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