enhanced linker script and startup

diff --git a/betty/Makefile b/betty/Makefile
index f6d465f..28184c3 100644 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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