avr: more general approach to fonts.

avr/modules/lcd2/font/main.asm

@@ -0,0 +1,167 @@
+; ***************************************************************************
+; copyright   : (C) 2025 by Martin Preuss
+; email       : martin@libchipcard.de
+;
+; ***************************************************************************
+; * This file is part of the project "AqHome".                              *
+; * Please see toplevel file COPYING of that project for license details.   *
+; ***************************************************************************
+
+
+
+; ***************************************************************************
+; code
+
+.cseg
+
+
+
+; ---------------------------------------------------------------------------
+; @routine FONT_RenderChar
+
+; @param R16    character to write
+; @param R1:R0  background color
+; @param R3:R2  foreground color
+; @param Z      pointer to font
+; @param X      pointer to RAM to store data to
+; @param r18    char width in pixel
+; @param r19    char height in pixel
+; @clobbers any, !Z
+
+FONT_RenderChar:
+  ldi r23, FONT_FN_RENDER
+  rjmp fontCallHandler
+; @end
+
+
+
+
+; ---------------------------------------------------------------------------
+; @routine FONT_GetCharWidth
+
+; @param  Z      pointer to font
+; @return R16    character width for given character set
+; @clobbers any, !Z
+
+FONT_GetCharWidth:
+  ldi r23, FONT_FN_GETCHARWIDTH
+  rjmp fontCallHandler
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine FONT_GetCharHeight
+
+; @param  Z      pointer to font
+; @return R16    character height for given character set
+; @clobbers any, !Z
+
+FONT_GetCharHeight:
+  ldi r23, FONT_FN_GETCHARHEIGHT
+  rjmp fontCallHandler
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine FONT_GetStringWidth
+
+; @param  Z      pointer to font
+; @param  X      pointer to null-terminated string in flash
+; @return R16    character width for given character set
+; @clobbers any, !Z
+
+FONT_GetStringWidthFlash:
+  ldi r23, FONT_FN_GETSTRINGWIDTH
+  rjmp fontCallHandler
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine FONT_GetStringHeight
+
+; @param  Z      pointer to font
+; @param  X      pointer to null-terminated string in flash
+; @return R16    character width for given character set
+; @clobbers any, !Z
+
+FONT_GetStringHeight:
+  ldi r23, FONT_FN_GETSTRINGHEIGHT
+  rjmp fontCallHandler
+; @end
+
+
+
+
+
+; ---------------------------------------------------------------------------
+; @routine fontCallHandler
+;
+; @param r23 function number
+; @param Z   pointer to font
+
+fontCallHandler:
+  lpm r17, Z+
+  push r17
+  lpm r17, Z
+  push r17
+  sbiw zh:zl, 1
+  ret
+; @end
+
+
+
+
+; ---------------------------------------------------------------------------
+; @routine FONT_GenericHandler
+;
+; Generic handler for font functions.
+; @param R23 function to call (see @ref FONT_FN_RENDER et al)
+
+FONT_GenericHandler:
+  cpi r23, FONT_FN_GETCHARWIDTH
+  breq fontGenericFnGetCharWidth
+  cpi r23, FONT_FN_GETCHARHEIGHT
+  breq fontGenericFnGetCharHeight
+  cpi r23, FONT_FN_GETSTRINGWIDTH
+  breq fontGenericFnGetStringWidth
+  cpi r23, FONT_FN_GETSTRINGHEIGHT
+  breq fontGenericFnGetStringHeight
+  ret
+fontGenericFnGetCharWidth:
+  adiw zh:zl, FONT_OFFS_WIDTH
+  ld r16, X
+  sbiw zh:zl, FONT_OFFS_WIDTH
+  ret
+fontGenericFnGetCharHeight:
+  adiw zh:zl, FONT_OFFS_HEIGHT
+  ld r16, X
+  sbiw zh:zl, FONT_OFFS_HEIGHT
+  ret
+fontGenericFnGetStringWidth:
+  adiw zh:zl, FONT_OFFS_WIDTH
+  ld r17, X
+  sbiw zh:zl, FONT_OFFS_WIDTH
+  clr r16
+  push zl
+    push zh
+      mov zl, xl
+      mov zh, xh
+fontGenericFnGetStringWidth_loop:
+        lpm r18, Z+
+        tst r18
+        breq fontGenericFnGetStringWidth_loopEnd
+        add r16, r17
+      rjmp fontGenericFnGetStringWidth_loop
+fontGenericFnGetStringWidth_loopEnd:
+    pop zh
+  pop zl
+  ret
+fontGenericFnGetStringHeight:
+  rjmp fontGenericFnGetCharHeight ; for now monospace fonts only
+; @end
+
+
+