X-Git-Url: https://hackdaworld.org/gitweb/?p=my-code%2Farm.git;a=blobdiff_plain;f=betty%2Fstartup.s;h=d393d32a35e0763ebc95a8b32f0401811829fcc7;hp=7cf1e107b3c222dc9faf006a31bf28d801b62dc4;hb=916c8dd1dfa2414ae8b58ab1e3d477b24c553815;hpb=026d6884ee8185fe08296b31d4bb570662cf2add

diff --git a/betty/startup.s b/betty/startup.s
index 7cf1e10..d393d32 100644
--- a/betty/startup.s
+++ b/betty/startup.s
@@ -49,19 +49,33 @@
 .arm
 
 	# exception handling must go to the very beginning
-
-	b handler_reset
-	b interrupt_handler_undef_instruction
-	b interrupt_handler_soft_ir
-	b interrupt_handler_prefetch_abort
-	b interrupt_handler_data_abort
+	#
+	# concerning irq:
+	#  - the ldr is at 0x18
+	#  - pc will be 0x18 + 8 at the moment of ldr (pipeline)
+	#  - substract 0xff0 => 0xfffff030
+	#  - that's the vectored address register
+	#  - the vic put in there the address of our service routine
+
+	ldr pc, handler_reset
+	ldr pc, handler_undef_instruction
+	ldr pc, handler_soft_ir
+	ldr pc, handler_prefetch_abort
+	ldr pc, handler_data_abort
 	nop
-	b interrupt_handler_irq
-	b interrupt_handler_fiq
+	ldr pc, [pc, #-0xff0]
+	ldr pc, handler_fiq
+
+handler_reset: .word handle_reset
+handler_undef_instruction: .word interrupt_handler_undef_instruction
+handler_soft_ir: .word interrupt_handler_soft_ir
+handler_prefetch_abort: .word interrupt_handler_prefetch_abort
+handler_data_abort: .word interrupt_handler_data_abort
+handler_fiq: .word interrupt_handler_fiq
 
 	# reset handling goes here
 
-handler_reset:
+handle_reset:
 
 	# init stack pointer for each mode + set stack limit
 
@@ -94,12 +108,15 @@ handler_reset:
 	ldr r0, =stack_limit
 	mov sl, r0
 
-	# copy data section
+	# copy data section (only if we are in flash <=> _etext != _data)
 
 	ldr r1, =_etext
 	ldr r2, =_data
 	ldr r3, =_edata
 
+	cmp r1, r2
+	beq start_of_c_code
+
 copy_data_loop:
 
 	cmp r2, r3
@@ -109,6 +126,8 @@ copy_data_loop:
 
 	# jump to c code
 
+start_of_c_code:
+
 	adr lr, loop_forever
 	mov r0, #0
 	mov r1, #0