terom@38: ;; Basic LED matrix fonts
terom@38: ;; vim: set ft=avr:
terom@38: 
terom@38: .cseg
terom@38: 
terom@38: ;; Font definition
terom@38: ; Defines FONT_8x6 symbol
terom@38: .include "font.def"
terom@38: 
terom@38: ; Font to use
terom@38: .set FONT_TABLE     = FONT_8x6
terom@38: .set FONT_START     = FONT_8x6_START
terom@38: .set FONT_END       = FONT_8x6_END
terom@38: .set FONT_COLS      = FONT_8x6_COLS
terom@38: .set FONT_ROWS      = FONT_8x6_ROWS     ; XXX: fixed to 8
terom@38: 
terom@38: ;; Render the given ASCII char into the given buffer
terom@38: ; Input:    r16 - ASCII char code
terom@38: ;           Y   - dest buf (Wx8 column data)
terom@38: Font_Render:
terom@38:     ; Test char index
terom@38: 
terom@38:         ; test under-range
terom@38:         ldi     r17, FONT_START
terom@38:         cp      r16, r17
terom@39:         brlt    font_r_invalid
terom@38: 
terom@38:         ; test over-range
terom@38:         ldi     r17, FONT_END
terom@38:         cp      r17, r16
terom@39:         brlt    font_r_invalid
terom@38: 
terom@38:         ; compute offset in chars (r16)
terom@38:         subi    r16, FONT_START
terom@38: 
terom@39:         ; ok
terom@39:         rjmp    font_r_render
terom@39: 
terom@39: font_r_invalid:
terom@39:         ; use first sym
terom@39:         ldi     r16, 0
terom@39: 
terom@39:     cbi         PORTD, PIND7
terom@39: 
terom@39: font_r_render:
terom@38:         ; compute offset in bytes (r1:r0)
terom@38:         ldi     r17, FONT_COLS
terom@38:         mul     r16, r17
terom@38: 
terom@38:         ; font table start offset from words
terom@38:         ldi     ZL, low(FONT_TABLE * 2)
terom@38:         ldi     ZH, high(FONT_TABLE * 2)
terom@38: 
terom@38:         ; apply offset
terom@38:         add     ZL, r0
terom@38:         adc     ZH, r1
terom@38: 
terom@38:     ; Copy column pixel data
terom@38:         ; count columns
terom@38:         ldi     r16, FONT_COLS
terom@39: font_r_cpy:
terom@38:         
terom@38:         ; copy via r17
terom@38:         lpm     r17, Z+
terom@38:         st      Y+, r17
terom@38: 
terom@38:         dec     r16
terom@39:         brne    font_r_cpy
terom@38: 
terom@38: 
terom@38:     ; Done
terom@38:         ret
terom@38: