reduce size of net buffers from 32 to 28.

allows us to use 10 buffers in R05.

avr/modules/network/buffer.asm

@@ -124,6 +124,8 @@ NET_Buffer_ReleaseByNum_end:
 NET_Buffer_Locate:
   cpi r16, NET_BUFFERS_NUM
   brcc NET_Buffer_Locate_end ; out of range
+
+.if NET_BUFFERS_SIZE == 32
   mov xh, r16  ; * 256
   clr xl
   lsr xh       ; *128
@@ -132,10 +134,31 @@ NET_Buffer_Locate:
   ror xl
   lsr xh       ; *32
   ror xl
+.elif NET_BUFFERS_SIZE == 28
+  clr r17
+  mov xl, r16  ; * 256
+  clr xh
+  lsl xl       ; * 2
+  rol xh
+  add xl, r16  ; * 3
+  adc xh, r17
+  lsl xl       ; * 6
+  rol xh
+  add xl, r16  ; * 7
+  adc xh, r17
+  lsl xl       ; * 14
+  rol xh
+  lsl xl       ; * 28
+  rol xh
+.else
+.error "Unhandled buffer size"
+.endif
+
   ldi r17, LOW(netBuffers)
   add xl, r17
   ldi r17, HIGH(netBuffers)
   adc xh, r17
+  
   sec
 NET_Buffer_Locate_end:
   ret

avr/modules/network/defs.asm

@@ -10,7 +10,7 @@
 
 ; defs
 
-.equ NET_BUFFERS_SIZE                   = 32 ; CAVE: need to adapt routine NET_Buffer_Locate when changing this value!!
+.equ NET_BUFFERS_SIZE                   = 28 ; CAVE: need to adapt routine NET_Buffer_Locate when changing this value!!
 
 .equ NET_MSGNUMINBUF_SIZE               =  6 ; max buffer nums in ringbuffer (global incoming)