From: hackbard <hackbard@staubsauger.localdomain>
Date: Fri, 14 Sep 2007 22:22:31 +0000 (+0200)
Subject: enhanced linker script and startup
X-Git-Url: https://hackdaworld.org/gitweb/?p=my-code%2Farm.git;a=commitdiff_plain;h=26b834d1801d8453bb25b6b427a6b6c3b131cf57

enhanced linker script and startup
---

diff --git a/betty/Makefile b/betty/Makefile
index f6d465f..28184c3 100644
--- a/betty/Makefile
+++ b/betty/Makefile
@@ -20,7 +20,7 @@ CROSS_TARGET = fwbc.hex fwflash.hex betty.hex
 
 # betty deps
 BETTY_DEPS = system.o uart.o buttons.o spi.o display.o flash.o functions.o
-#BETTY_DEPS += pffs.o
+BETTY_DEPS += interrupts.o #pffs.o
 
 # all projects
 all: $(HOST_TARGET) $(CROSS_TARGET)
@@ -48,8 +48,8 @@ arm: arm_clean $(CROSS_TARGET)
 	$(CROSS_AS) $(CROSS_ASLAGS) -o $@ $<
 
 # .elf out of .o
-%.elf: %.o startup.o
-	$(CROSS_LD) $(CROSS_RAM_LDFLAGS) startup.o -o $@ $<
+%.elf: %.o startup.o interrupts.o
+	$(CROSS_LD) $(CROSS_RAM_LDFLAGS) startup.o interrupts.o -o $@ $<
 
 # betty is special ;)
 betty.elf: betty.o startup.o $(BETTY_DEPS)
diff --git a/betty/lpc2220_ram.ld b/betty/lpc2220_ram.ld
index c6fd14d..7356893 100644
--- a/betty/lpc2220_ram.ld
+++ b/betty/lpc2220_ram.ld
@@ -20,7 +20,14 @@ SECTIONS {
 
 	. = ALIGN(4);
 
-	.data : { *(.data) }		/* initialized data */
+	/* define end of text symbol */
+	_etext = .;
+
+	.data : {			/* initialized data */
+		_data = .;
+		*(.data)
+		_edata = .;
+	}
 
 	. = ALIGN(4);
 
diff --git a/betty/lpc2220_rom.ld b/betty/lpc2220_rom.ld
index ab48644..92a99a0 100644
--- a/betty/lpc2220_rom.ld
+++ b/betty/lpc2220_rom.ld
@@ -32,12 +32,27 @@ SECTIONS {
 
 	. = ALIGN(4);
 
+	/* define text end symbol */
+	_etext = .;
+	PROVIDE(etext = .);
+
 	/* initialized data */
-	.data : { *(.data) } > RAM AT FLASH_BANK0
+	.data : {
+		_data = .;
+		*(.data)
+	} > RAM AT > FLASH_BANK0
 
 	. = ALIGN(4);
 
+	/* define data end symbol */
+	_edata = .;
+	PROVIDE(edata = .);
+
 	/* uninitialized data */
-	.bss : { *(.bss) } > RAM AT FLASH_BANK0
+	.bss (NOLOAD) : { *(.bss) } > RAM
+
+	/* define bss end symbol */
+	_bss_end = .;
+	PROVIDE(bss_end = .);
 }
 
diff --git a/betty/startup.s b/betty/startup.s
index bc4ff41..af87f6e 100644
--- a/betty/startup.s
+++ b/betty/startup.s
@@ -16,10 +16,31 @@
 
 # stack
 
-.equ	stack_size,	(2*1024)
+.equ	stack_size,	(4*1024)
 .equ	stack_top,	sram_top
 .equ	stack_limit,	(sram_top-stack_size)
 
+.equ	stack_size_fiq,		64
+.equ	stack_size_irq,		256
+.equ	stack_size_supervisor,	64
+.equ	stack_size_abort,	64
+.equ	stack_size_undefined,	64
+.equ	stack_size_system,	1024
+
+# arm modes - control bits of the program status register
+# ref: chapter 2.8, arm7tdmi-s technical reference manual
+
+.equ	mode_user,		0x10
+.equ	mode_fiq,		0x11
+.equ	mode_irq,		0x12
+.equ	mode_supervisor,	0x13
+.equ	mode_abort,		0x17
+.equ	mode_undefined,		0x1b
+.equ	mode_system,		0x1f
+
+.equ	fiq_disable,	0x40
+.equ	irq_disable,	0x80
+
 #
 # the startup code
 #
@@ -27,13 +48,72 @@
 .text
 .arm
 
-	# init stack pointer
+	# exception handling must go to the very beginning
+
+	b handler_reset
+	b handler_undef_instruction
+	b handler_soft_ir
+	b handler_prefetch_abort
+	b handler_data_abort
+	nop
+	b handler_irq
+	b handler_fiq
+
+	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_irq: .word interrupt_handler_irq
+	handler_fiq: .word interrupt_handler_fiq
+
+	# reset handling goes here
+
+handler_reset:
+
+	# init stack pointer for each mode + set stack limit
 
 	ldr r0, =sram_top
+
+	msr cpsr_c, #mode_undefined|irq_disable|fiq_disable
 	mov sp, r0
+	sub r0, r0, #stack_size_undefined
+
+	msr cpsr_c, #mode_abort|irq_disable|fiq_disable
+	mov sp, r0
+	sub r0, r0, #stack_size_abort
+
+	msr cpsr_c, #mode_fiq|irq_disable|fiq_disable
+	mov sp, r0
+	sub r0, r0, #stack_size_fiq
+
+	msr cpsr_c, #mode_irq|irq_disable|fiq_disable
+	mov sp, r0
+	sub r0, r0, #stack_size_irq
+
+	msr cpsr_c, #mode_supervisor|irq_disable|fiq_disable
+	mov sp, r0
+	sub r0, r0, #stack_size_supervisor
+
+	msr cpsr_c, #mode_system|irq_disable|fiq_disable
+	mov sp, r0
+	sub r0, r0, #stack_size_system
+
 	ldr r0, =stack_limit
 	mov sl, r0
 
+	# copy data section
+
+	ldr r1, =_etext
+	ldr r2, =_data
+	ldr r3, =_edata
+
+copy_data_loop:
+
+	cmp r2, r3
+	ldrlo r0, [r1], #4
+	strlo r0, [r2], #4
+	blo copy_data_loop
+
 	# jump to c code
 
 	adr lr, loop_forever