more work on pages and ressources.

avr/common/0BUILD

@@ -32,6 +32,7 @@
     tree_t.asm
     eeprom-r.asm
     eeprom-w.asm
+    ressource.asm
   </extradist>
 
 </gwbuild>

avr/common/ressource.asm

@@ -0,0 +1,64 @@
+; ***************************************************************************
+; 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.   *
+; ***************************************************************************
+
+#ifndef AQH_AVR_COMMON_RESSOURCE_H
+#define AQH_AVR_COMMON_RESSOURCE_H
+
+
+; ***************************************************************************
+; defs
+
+
+
+; ***************************************************************************
+; code
+
+.cseg
+
+
+; ---------------------------------------------------------------------------
+; @routine RES_GetRessource
+;
+; The Ressource table has one entry for every ressource handled by this table.
+; The first entry contains the number of ressource entries in the table.
+; All following entries contain byte pointer addresses (for LPM) to ressources.
+; Ressource ids start with zero.
+;
+; @param r17:r16 ressource id (starting with 0)
+; @param Z pointer to start of ressources in FLASH (byte address)
+; @return CF set if ressource found, cleared otherwise
+; @return Z if CF set: pointer to ressource (byte address)
+; @clobbers r16, r17, r18
+
+RES_GetRessource:
+  lpm r18, Z+   ; first entry: number of entries in table
+  cp r16, r18   ; id must be < num entries
+  lpm r18, Z+   ; Z points to first entry now
+  cpc r17, r18
+  brcc RES_GetRessource_ret
+RES_GetRessource_getRessource:
+  lsl r16       ; byte address, so we need to add ressource id twice (i.e. *2)
+  rol r17
+  add zl, r16
+  add zh, r17
+  lpm r16, Z+
+  lpm r17, Z+
+  mov zl, r16
+  mov zh, r17
+  sec
+RES_GetRessource_ret:
+  ret
+; @end
+
+
+
+
+
+#endif
+