moved graphops into a dedicated sourcefile.

avr/devices/all/includes.asm

@@ -156,6 +156,7 @@
 .include "modules/lcd2/ili9341/defs.asm"
 .include "modules/lcd2/ili9341/main.asm"
 .include "modules/lcd2/ili9341/io_spi.asm"
+.include "modules/lcd2/ili9341/graphops.asm"
 .include "modules/lcd2/ili9341/text.asm"
 #endif
 

avr/modules/lcd2/font/font1.asm

@@ -26,7 +26,7 @@
 
 font1_8x8:
 ; header
-  rjmp font8x8MonoRenderCharacter               ; renderFn
+  .dw font8x8MonoRenderCharacter                ; renderFn
   .db 128, 0                                    ; needed buffer size
   .db 8, 8                                      ; width, height of chars
   .db 32, 64                                    ; first char, num of chars in font

avr/modules/lcd2/font/font8x8.asm

@@ -31,9 +31,6 @@
 font8x8MonoRenderCharacter:
   push zl
     push zh
-      lsl zl
-      rol zh
-    
       rcall font8x8GetCharPosInFont8x8         ; (r17, r24, r25, z)
       ldi r25, 8   ; 8 bytes
 font8x8MonoRenderCharacter_loop1:

avr/modules/lcd2/ili9341/graphops.asm

@@ -0,0 +1,337 @@
+; ***************************************************************************
+; 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.   *
+; ***************************************************************************
+
+
+; ---------------------------------------------------------------------------
+; @routine ili9341SetAddressWindow
+;
+; @param r5:r4   X0
+; @param r7:r6   Y0
+; @param r9:r8   W
+; @param r11:r10 H
+; @clobbers R16, r20, r21
+
+ili9341SetAddressWindow:
+  ; calc XEnd (=X+W-1)
+  mov r20, r8
+  mov r21, r9
+  add r20, r4
+  adc r21, r5
+  subi r20, 1
+  sbci r21, 0
+
+  ; send column address
+  ldi r16, ILI9341_CMD_CASET
+  rcall ili9341SendCommand
+  ; X0
+  mov r16, r5
+  rcall ili9341SendData
+  mov r16, r4
+  rcall ili9341SendData
+  ; X1
+  mov r16, r21
+  rcall ili9341SendData
+  mov r16, r20
+  rcall ili9341SendData
+
+  ; calc YEnd (=Y+H-1)
+  mov r20, r10
+  mov r21, r11
+  add r20, r6
+  adc r21, r7
+  subi r20, 1
+  sbci r21, 0
+
+  ; send row address
+  ldi r16, ILI9341_CMD_PASET
+  rcall ili9341SendCommand
+  ; Y0
+  mov r16, r7
+  rcall ili9341SendData
+  mov r16, r6
+  rcall ili9341SendData
+  ; Y1
+  mov r16, r21
+  rcall ili9341SendData
+  mov r16, r20
+  rcall ili9341SendData
+
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine ILI9341_FillRect
+; @param r3:r2 color
+; @param r5:r4   X0
+; @param r7:r6   Y0
+; @param r9:r8   X1/W
+; @param r11:r10 Y1/H
+
+ILI9341_FillRect:
+  push r15
+    in r15, SREG
+    cli
+
+    rcall ili9341BeginSpi         ; (R16, R17)
+    rcall ili9341SetAddressWindow ; (R16, r20, r21)
+  
+    mov r18, r2   ; color
+    mov r19, r3
+    mov r22, r10  ; H low
+    mov r23, r11  ; H high
+    ldi r16, ILI9341_CMD_RAMWR                 ; start writing ro RAM
+    rcall ili9341SendCommand
+  
+    cbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN       ; SS low
+    sbi ILI9341_DC_OUTPUT, ILI9341_DC_PIN   ; D high (DATA)
+ILI9341_FillRect_loopH:
+      mov r24, r8 ; W low
+      mov r25, r9 ; W high
+ILI9341_FillRect_loopW:
+        mov r16, r19
+        rcall SPIHW_MasterTransfer
+        mov r16, r18
+        rcall SPIHW_MasterTransfer
+        sbiw r25:r24, 1
+      brne ILI9341_FillRect_loopW
+      mov r24, r22    ; H low
+      mov r25, r23    ; H high
+      sbiw r25:r24, 1 ; dec
+      mov r22, r24    ; save in r23:r22
+      mov r23, r25
+    brne ILI9341_FillRect_loopH
+    sbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN        ; SS high
+    rcall ili9341EndSpi
+    out SREG, r15
+  pop r15
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine ili9341BitBlit
+
+; @param  r5:r4   X (dest)
+; @param  r7:r6   Y (dest)
+; @param  r9:r8   W
+; @param  r11:r10 H
+; @param  X       source data pointer (RAM)
+; @clobbers r16, r22, r23, r24, r25, X (r17, r20, r21)
+
+ili9341BitBlit:
+  push r15
+    in r15, SREG
+    cli
+
+    rcall ili9341BeginSpi                   ; (r16, r17)
+    rcall ili9341SetAddressWindow           ; (R16, R20, R21)
+  
+    ldi r16, ILI9341_CMD_RAMWR              ; start writing ro RAM
+    rcall ili9341SendCommand
+
+    mov r22, r10
+    mov r23, r11
+    cbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN       ; SS low
+    sbi ILI9341_DC_OUTPUT, ILI9341_DC_PIN   ; D high (DATA)
+ili9341BitBlit_loopH:
+      mov r24, r8
+      mov r25, r9
+ili9341BitBlit_loopW:
+        ld r18, X+
+        ld r19, X+
+        mov r16, r19
+        rcall SPIHW_MasterTransfer           ; (R16)
+        mov r16, r18
+        rcall SPIHW_MasterTransfer           ; (R16)
+        sbiw r25:r24, 1
+      brne  ili9341BitBlit_loopW
+      mov r24, r22
+      mov r25, r23
+      sbiw r25:r24, 1
+      mov r22, r24
+      mov r23, r25
+    brne ili9341BitBlit_loopH
+    sbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN        ; SS high
+    rcall ili9341EndSpi                      ; (R16)
+    out SREG, r15
+  pop r15
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine ili9341BitBlitStretch2
+
+; @param  r5:r4   X (dest)
+; @param  r7:r6   Y (dest)
+; @param  r9:r8   W
+; @param  r11:r10 H
+; @param  X       source data pointer (RAM)
+; @clobbers r16, r22, r23, r24, r25, X (r17, r18, r19, r20, r21)
+
+ili9341BitBlitStretch2:
+  push r15
+    in r15, SREG
+    cli
+
+    push r8
+      push r9
+        push r10
+          push r11
+            ; width
+            lsl r8  ; x2
+            rol r9
+            ; height
+            lsl r10  ; x2
+            rol r11
+            
+            rcall ili9341BeginSpi                       ; (r16, r17)
+            rcall ili9341SetAddressWindow               ; (R16, R20, R21)
+          pop r11
+        pop r10
+      pop r9
+    pop r8
+    ldi r16, ILI9341_CMD_RAMWR                  ; start writing ro RAM
+    rcall ili9341SendCommand
+
+    mov r22, r10
+    mov r23, r11
+    cbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN           ; SS low
+    sbi ILI9341_DC_OUTPUT, ILI9341_DC_PIN       ; D high (DATA)
+    ldi r17, 2
+ili9341BitBlitStretch2_loopH:
+      mov r20, xl                               ; preserve for next run
+      mov r21, xh
+      rcall ili9341BitBlitStretchNWriteLine     ; (r16, r17, r18, r19, r24, r25, X)
+      mov xl, r20
+      mov xh, r21
+      rcall ili9341BitBlitStretchNWriteLine     ; (r16, r17, r18, r19, r24, r25, X)
+      mov r24, r22
+      mov r25, r23
+      sbiw r25:r24, 1
+      mov r22, r24
+      mov r23, r25
+    brne ili9341BitBlitStretch2_loopH
+    sbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN           ; SS high
+    rcall ili9341EndSpi                         ; (R16)
+    out SREG, r15
+  pop r15
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine ili9341BitBlitStretch4
+
+; @param  r5:r4   X (dest)
+; @param  r7:r6   Y (dest)
+; @param  r9:r8   W
+; @param  r11:r10 H
+; @param  X       source data pointer (RAM)
+; @clobbers r16, r22, r23, r24, r25, X (r17, r20, r21)
+
+ili9341BitBlitStretch4:
+  push r15
+    in r15, SREG
+    cli
+
+    push r8
+      push r9
+        push r10
+          push r11
+            ; width
+            lsl r8  ; x2
+            rol r9
+            lsl r8  ; x4
+            rol r9
+            ; height
+            lsl r10  ; x2
+            rol r11
+            lsl r10  ; x4
+            rol r11
+            
+            rcall ili9341BeginSpi                       ; (r16, r17)
+            rcall ili9341SetAddressWindow               ; (R16, R20, R21)
+          pop r11
+        pop r10
+      pop r9
+    pop r8
+    ldi r16, ILI9341_CMD_RAMWR                  ; start writing ro RAM
+    rcall ili9341SendCommand
+
+    mov r22, r10
+    mov r23, r11
+    ldi r17, 4
+    cbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN           ; SS low
+    sbi ILI9341_DC_OUTPUT, ILI9341_DC_PIN       ; D high (DATA)
+ili9341BitBlitStretch4_loopH:
+      mov r20, xl                               ; preserve for next run
+      mov r21, xh
+      rcall ili9341BitBlitStretchNWriteLine     ; (r16, r17, r18, r19, r24, r25, X)
+      mov xl, r20
+      mov xh, r21
+      rcall ili9341BitBlitStretchNWriteLine     ; (r16, r17, r18, r19, r24, r25, X)
+      mov xl, r20
+      mov xh, r21
+      rcall ili9341BitBlitStretchNWriteLine     ; (r16, r17, r18, r19, r24, r25, X)
+      mov xl, r20
+      mov xh, r21
+      rcall ili9341BitBlitStretchNWriteLine     ; (r16, r17, r18, r19, r24, r25, X)
+      mov r24, r22
+      mov r25, r23
+      sbiw r25:r24, 1
+      mov r22, r24
+      mov r23, r25
+    brne ili9341BitBlitStretch4_loopH
+    sbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN        ; SS high
+    rcall ili9341EndSpi                      ; (R16)
+    out SREG, r15
+  pop r15
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine ili9341BitBlitStretchNWriteLine
+
+; @param r9:r8 width
+; @param r17 repeat factor
+; @param X source position of line
+; @clobbers r16, r17, r18, r19, r24, r25, X
+
+ili9341BitBlitStretchNWriteLine:
+    mov r24, r8
+    mov r25, r9
+ili9341BitBlitStretchNWriteLine_loop1:
+    ld r18, X+
+    ld r19, X+
+    push r17
+ili9341BitBlitStretchNWriteLine_loop2:
+        mov r16, r19
+        rcall SPIHW_MasterTransfer           ; (R16)
+        mov r16, r18
+        rcall SPIHW_MasterTransfer           ; (R16)
+        dec r17
+      brne ili9341BitBlitStretchNWriteLine_loop2
+    pop r17
+    sbiw r25:r24, 1
+  brne  ili9341BitBlitStretchNWriteLine_loop1
+  ret
+; @end
+
+
+
+
+

avr/modules/lcd2/ili9341/main.asm

@@ -97,8 +97,8 @@ ILI9341_Init:
   mov r7, r16
   
 ; set font pos
-  ldi zl, LOW(font1_8x8)
+  ldi zl, LOW(font1_8x8*2)
-  ldi zh, HIGH(font1_8x8)
+  ldi zh, HIGH(font1_8x8*2)
   
 ; set buffer pos
 ;  ldi xl, LOW(ILI9341_buffer)
@@ -279,328 +279,12 @@ ILI9341_FillScreen:
 
 
 
-; ---------------------------------------------------------------------------
-; @routine ili9341SetAddressWindow
-;
-; @param r5:r4   X0
-; @param r7:r6   Y0
-; @param r9:r8   W
-; @param r11:r10 H
-; @clobbers R16, r20, r21
-
-ili9341SetAddressWindow:
-  ; calc XEnd (=X+W-1)
-  mov r20, r8
-  mov r21, r9
-  add r20, r4
-  adc r21, r5
-  subi r20, 1
-  sbci r21, 0
-
-  ; send column address
-  ldi r16, ILI9341_CMD_CASET
-  rcall ili9341SendCommand
-  ; X0
-  mov r16, r5
-  rcall ili9341SendData
-  mov r16, r4
-  rcall ili9341SendData
-  ; X1
-  mov r16, r21
-  rcall ili9341SendData
-  mov r16, r20
-  rcall ili9341SendData
-
-  ; calc YEnd (=Y+H-1)
-  mov r20, r10
-  mov r21, r11
-  add r20, r6
-  adc r21, r7
-  subi r20, 1
-  sbci r21, 0
-
-  ; send row address
-  ldi r16, ILI9341_CMD_PASET
-  rcall ili9341SendCommand
-  ; Y0
-  mov r16, r7
-  rcall ili9341SendData
-  mov r16, r6
-  rcall ili9341SendData
-  ; Y1
-  mov r16, r21
-  rcall ili9341SendData
-  mov r16, r20
-  rcall ili9341SendData
-
-  ret
-; @end
 
 
 
-; ---------------------------------------------------------------------------
-; @routine ILI9341_FillRect
-; @param r3:r2 color
-; @param r5:r4   X0
-; @param r7:r6   Y0
-; @param r9:r8   X1/W
-; @param r11:r10 Y1/H
-
-ILI9341_FillRect:
-  push r15
-    in r15, SREG
-    cli
-
-    rcall ili9341BeginSpi         ; (R16, R17)
-    rcall ili9341SetAddressWindow ; (R16, r20, r21)
-  
-    mov r18, r2   ; color
-    mov r19, r3
-    mov r22, r10  ; H low
-    mov r23, r11  ; H high
-    ldi r16, ILI9341_CMD_RAMWR                 ; start writing ro RAM
-    rcall ili9341SendCommand
-  
-    cbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN       ; SS low
-    sbi ILI9341_DC_OUTPUT, ILI9341_DC_PIN   ; D high (DATA)
-ILI9341_FillRect_loopH:
-      mov r24, r8 ; W low
-      mov r25, r9 ; W high
-ILI9341_FillRect_loopW:
-        mov r16, r19
-        rcall SPIHW_MasterTransfer
-        mov r16, r18
-        rcall SPIHW_MasterTransfer
-        sbiw r25:r24, 1
-      brne ILI9341_FillRect_loopW
-      mov r24, r22    ; H low
-      mov r25, r23    ; H high
-      sbiw r25:r24, 1 ; dec
-      mov r22, r24    ; save in r23:r22
-      mov r23, r25
-    brne ILI9341_FillRect_loopH
-    sbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN        ; SS high
-    rcall ili9341EndSpi
-    out SREG, r15
-  pop r15
-  ret
-; @end
 
 
 
-; ---------------------------------------------------------------------------
-; @routine ili9341BitBlit
-
-; @param  r5:r4   X (dest)
-; @param  r7:r6   Y (dest)
-; @param  r9:r8   W
-; @param  r11:r10 H
-; @param  X       source data pointer (RAM)
-; @clobbers r16, r22, r23, r24, r25, X (r17, r20, r21)
-
-ili9341BitBlit:
-  push r15
-    in r15, SREG
-    cli
-
-    rcall ili9341BeginSpi                   ; (r16, r17)
-    rcall ili9341SetAddressWindow           ; (R16, R20, R21)
-  
-    ldi r16, ILI9341_CMD_RAMWR              ; start writing ro RAM
-    rcall ili9341SendCommand
-
-    mov r22, r10
-    mov r23, r11
-    cbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN       ; SS low
-    sbi ILI9341_DC_OUTPUT, ILI9341_DC_PIN   ; D high (DATA)
-ili9341BitBlit_loopH:
-      mov r24, r8
-      mov r25, r9
-ili9341BitBlit_loopW:
-        ld r18, X+
-        ld r19, X+
-        mov r16, r19
-        rcall SPIHW_MasterTransfer           ; (R16)
-        mov r16, r18
-        rcall SPIHW_MasterTransfer           ; (R16)
-        sbiw r25:r24, 1
-      brne  ili9341BitBlit_loopW
-      mov r24, r22
-      mov r25, r23
-      sbiw r25:r24, 1
-      mov r22, r24
-      mov r23, r25
-    brne ili9341BitBlit_loopH
-    sbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN        ; SS high
-    rcall ili9341EndSpi                      ; (R16)
-    out SREG, r15
-  pop r15
-  ret
-; @end
-
-
-
-; ---------------------------------------------------------------------------
-; @routine ili9341BitBlitStretch2
-
-; @param  r5:r4   X (dest)
-; @param  r7:r6   Y (dest)
-; @param  r9:r8   W
-; @param  r11:r10 H
-; @param  X       source data pointer (RAM)
-; @clobbers r16, r22, r23, r24, r25, X (r17, r18, r19, r20, r21)
-
-ili9341BitBlitStretch2:
-  push r15
-    in r15, SREG
-    cli
-
-    push r8
-      push r9
-        push r10
-          push r11
-            ; width
-            lsl r8  ; x2
-            rol r9
-            ; height
-            lsl r10  ; x2
-            rol r11
-            
-            rcall ili9341BeginSpi                       ; (r16, r17)
-            rcall ili9341SetAddressWindow               ; (R16, R20, R21)
-          pop r11
-        pop r10
-      pop r9
-    pop r8
-    ldi r16, ILI9341_CMD_RAMWR                  ; start writing ro RAM
-    rcall ili9341SendCommand
-
-    mov r22, r10
-    mov r23, r11
-    cbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN           ; SS low
-    sbi ILI9341_DC_OUTPUT, ILI9341_DC_PIN       ; D high (DATA)
-    ldi r17, 2
-ili9341BitBlitStretch2_loopH:
-      mov r20, xl                               ; preserve for next run
-      mov r21, xh
-      rcall ili9341BitBlitStretchNWriteLine     ; (r16, r17, r18, r19, r24, r25, X)
-      mov xl, r20
-      mov xh, r21
-      rcall ili9341BitBlitStretchNWriteLine     ; (r16, r17, r18, r19, r24, r25, X)
-      mov r24, r22
-      mov r25, r23
-      sbiw r25:r24, 1
-      mov r22, r24
-      mov r23, r25
-    brne ili9341BitBlitStretch2_loopH
-    sbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN           ; SS high
-    rcall ili9341EndSpi                         ; (R16)
-    out SREG, r15
-  pop r15
-  ret
-; @end
-
-
-
-; ---------------------------------------------------------------------------
-; @routine ili9341BitBlitStretch4
-
-; @param  r5:r4   X (dest)
-; @param  r7:r6   Y (dest)
-; @param  r9:r8   W
-; @param  r11:r10 H
-; @param  X       source data pointer (RAM)
-; @clobbers r16, r22, r23, r24, r25, X (r17, r20, r21)
-
-ili9341BitBlitStretch4:
-  push r15
-    in r15, SREG
-    cli
-
-    push r8
-      push r9
-        push r10
-          push r11
-            ; width
-            lsl r8  ; x2
-            rol r9
-            lsl r8  ; x4
-            rol r9
-            ; height
-            lsl r10  ; x2
-            rol r11
-            lsl r10  ; x4
-            rol r11
-            
-            rcall ili9341BeginSpi                       ; (r16, r17)
-            rcall ili9341SetAddressWindow               ; (R16, R20, R21)
-          pop r11
-        pop r10
-      pop r9
-    pop r8
-    ldi r16, ILI9341_CMD_RAMWR                  ; start writing ro RAM
-    rcall ili9341SendCommand
-
-    mov r22, r10
-    mov r23, r11
-    ldi r17, 4
-    cbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN           ; SS low
-    sbi ILI9341_DC_OUTPUT, ILI9341_DC_PIN       ; D high (DATA)
-ili9341BitBlitStretch4_loopH:
-      mov r20, xl                               ; preserve for next run
-      mov r21, xh
-      rcall ili9341BitBlitStretchNWriteLine     ; (r16, r17, r18, r19, r24, r25, X)
-      mov xl, r20
-      mov xh, r21
-      rcall ili9341BitBlitStretchNWriteLine     ; (r16, r17, r18, r19, r24, r25, X)
-      mov xl, r20
-      mov xh, r21
-      rcall ili9341BitBlitStretchNWriteLine     ; (r16, r17, r18, r19, r24, r25, X)
-      mov xl, r20
-      mov xh, r21
-      rcall ili9341BitBlitStretchNWriteLine     ; (r16, r17, r18, r19, r24, r25, X)
-      mov r24, r22
-      mov r25, r23
-      sbiw r25:r24, 1
-      mov r22, r24
-      mov r23, r25
-    brne ili9341BitBlitStretch4_loopH
-    sbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN        ; SS high
-    rcall ili9341EndSpi                      ; (R16)
-    out SREG, r15
-  pop r15
-  ret
-; @end
-
-
-
-; ---------------------------------------------------------------------------
-; @routine ili9341BitBlitStretchNWriteLine
-
-; @param r9:r8 width
-; @param r17 repeat factor
-; @param X source position of line
-; @clobbers r16, r17, r18, r19, r24, r25, X
-
-ili9341BitBlitStretchNWriteLine:
-    mov r24, r8
-    mov r25, r9
-ili9341BitBlitStretchNWriteLine_loop1:
-    ld r18, X+
-    ld r19, X+
-    push r17
-ili9341BitBlitStretchNWriteLine_loop2:
-        mov r16, r19
-        rcall SPIHW_MasterTransfer           ; (R16)
-        mov r16, r18
-        rcall SPIHW_MasterTransfer           ; (R16)
-        dec r17
-      brne ili9341BitBlitStretchNWriteLine_loop2
-    pop r17
-    sbiw r25:r24, 1
-  brne  ili9341BitBlitStretchNWriteLine_loop1
-  ret
-; @end
 
 
 

avr/modules/lcd2/ili9341/text.asm

@@ -23,13 +23,13 @@
 ; @param  r7:r6  Y
 ; @param  r1:r0  background color
 ; @param  r3:r2  foreground color
-; @param  Z      pointer to font (word address!)
+; @param  Z      pointer to font (byte address for LPM!)
 ; @param  X      pointer to RAM to store data to
 ; @return r5:r4  new X (advanced by character width)
 ; @clobbers r16 (r17, r20, r21, r22, r23, r24, r25, X)
 
 ili9341_WriteCharacterX1At:
-  rcall ili9341PrepareCharFromFont ; (r16, r17, r24, r25, z)
+  rcall ili9341FontRenderChar ; (r16, r17, r24, r25, z)
   rcall ili9341BitBlit             ; (r16, r17, r20, r21, r22, r23, r24, r25, X)
   ; advance X (add char width to X)
   add r4, r8
@@ -48,13 +48,13 @@ ili9341_WriteCharacterX1At:
 ; @param  r7:r6  Y
 ; @param  r1:r0  background color
 ; @param  r3:r2  foreground color
-; @param  Z      pointer to font (word address!)
+; @param  Z      pointer to font (byte address for LPM!)
 ; @param  X      pointer to RAM to store data to
 ; @return r5:r4  new X (advanced by character width)
 ; @clobbers r16 (r17, r18, r19, r20, r21, r22, r23, r24, r25, X)
 
 ili9341_WriteCharacterX2At:
-  rcall ili9341PrepareCharFromFont ; (r16, r17, r24, r25, z)
+  rcall ili9341FontRenderChar ; (r16, r17, r24, r25, z)
   rcall ili9341BitBlitStretch2     ; (r16, r17, r18, r19, r20, r21, r22, r23, r24, r25, X)
   ; advance X (add double char width to X)
   lsl r8      ; Wx2
@@ -74,13 +74,13 @@ ili9341_WriteCharacterX2At:
 ; @param  r7:r6  Y
 ; @param  r1:r0  background color
 ; @param  r3:r2  foreground color
-; @param  Z      pointer to font (word address!)
+; @param  Z      pointer to font (byte address for LPM!)
 ; @param  X      pointer to RAM to store data to
 ; @return r5:r4  new X (advanced by character width)
 ; @clobbers r16, r17, r18, r19, r24, r25, x, z
 
 ili9341_WriteCharacterX4At:
-  rcall ili9341PrepareCharFromFont ; (r16, r17, r24, r25, z)
+  rcall ili9341FontRenderChar ; (r16, r17, r24, r25, z)
   rcall ili9341BitBlitStretch4     ; (r16, r17, r20, r21, r22, r23, r24, r25, X)
   ; advance X (add quad char width to X)
   lsl r8      ; Wx2
@@ -97,7 +97,7 @@ ili9341_WriteCharacterX4At:
 
 
 ; ---------------------------------------------------------------------------
-; @routine ili9341PrepareCharFromFont
+; @routine ili9341FontRenderChar
 
 ; @param  R16     character to write
 ; @param  Z       pointer to font
@@ -106,7 +106,7 @@ ili9341_WriteCharacterX4At:
 ; @return r11:r10 character height in points
 ; @clobbers r16 (r17, r24, r25, z)
 
-ili9341PrepareCharFromFont:
+ili9341FontRenderChar:
   ; render character
   push xl
     push xh
@@ -129,9 +129,15 @@ ili9341PrepareCharFromFont:
 ; @routine ili9341JumpToFontRenderFn
 ;
 ; helper function to call function at the beginning of the given font
+; @clobbers r17
 
 ili9341JumpToFontRenderFn:
-  ijmp
+  lpm r17, Z+
+  push r17
+  lpm r17, Z
+  push r17
+  sbiw zh:zl, 1
+  ret
 ; @end