- added exception vector table.

S/W can write exception handler entry to this table.
  Exception handler can now reside anywhere in memory.

Committed on the Free edition of March Hare Software CVSNT Server.
Upgrade to CVS Suite for more features and support:
http://march-hare.com/cvsnt/


git-svn-id: http://moon:8086/svn/vhdl/trunk@494 cc03376c-175c-47c8-b038-4cd826a8556b

lib/CPUs/MIPS/bsp/examples/startup.S

@@ -9,11 +9,19 @@ argv:		.word		argv0
 		.section .start, "ax"
 		.extern _init
 		.extern dbg_init
+		.extern _exc_vect_start
+		.extern _xcpt_handler
 		.align	2
 		.globl _start
 _start:
 		.set	noreorder
+		j	init
+		nop		
+		.set	reorder
 
+		.text
+		.set	noreorder
+init:
 		# Set stack pointer 
 		la $sp, stack_ptr
 		# Set global pointer 
@@ -27,6 +35,17 @@ $zeroise:
 		bne $8, $9, $zeroise
 		addiu	$8, 4
 
+		# Install exception vector jump code
+		la $t1, _exc_vect_copy_start
+		la $t2, _exc_vect_copy_end
+		la $t0, _exc_vect_start
+
+$install:	lw	$v0, 0($t1)
+		addiu	$t1, 4
+		sw	$v0, 0($t0)
+		bne	$t1, $t2, $install
+		addiu	$t0, 4
+		
 		# Call _init
 		la $k0, _init
 		jalr $k0
@@ -41,6 +60,12 @@ $zeroise:
 		li	$a0, 1
 		la	$a1, argv
 
+		# Set user-mode
+		mfc0	$a0, $12
+		li	$a1, 3
+		or	$a0, $a1
+		mtc0	$a0, $12
+		
 		# Call main
 		la $k0, main
 		jalr $k0
@@ -52,5 +77,11 @@ _terminate:
 		la $t0, exit
 		jalr $t0
 		move $a0, $v0
+
+_exc_vect_copy_start:
+		la $k0, _xcpt_handler
+		jr $k0
+		nop
+_exc_vect_copy_end:
 		
 		.set	reorder