Completely separate DFU from application program, we now have a real bootloader.

DFU occupies 0x00100000 - 0x00100fff in flash, application starts at 0x00101000.
DFU also occupies the first couple of bytes in SRAM, application starts at 0x00200024.

In order to produce a samba-flashable image, first build dfu.bin by typing 
'make -f Makefule.dfu', succeeded by 'make TARGET=... DEBUG=... BOARD=...' and then 
concatenating the two files together, e.g. cat dfu.bin main_reqa.bin > flash.bin.

Actual flashing via DFU is still not operational, but will be implemented next


git-svn-id: https://svn.openpcd.org:2342/trunk@194 6dc7ffe9-61d6-0310-9af1-9938baff3ed1

7 files changed, 268 insertions, 193 deletions

diff --git a/firmware/src/os/dfu.c b/firmware/src/dfu/dfu.c
index f2bc0ca..f50b564 100644
--- a/firmware/src/os/dfu.c
+++ b/firmware/src/dfu/dfu.c
@@ -11,9 +11,8 @@
 #include <usb_dfu.h>
 #include <lib_AT91SAM7.h>
 
-#include <os/dfu.h>
+#include <dfu/dfu.h>
 #include <os/pcd_enumerate.h>
-#include <os/req_ctx.h>
 #include "../openpcd.h"
 
 /* If debug is enabled, we need to access debug functions from flash
@@ -29,7 +28,7 @@
 #endif
 
 
-void __dfufunc udp_init(void)
+static void __dfufunc udp_init(void)
 {
 	/* Set the PLL USB Divider */
 	AT91C_BASE_CKGR->CKGR_PLLR |= AT91C_CKGR_USBDIV_1;
@@ -107,7 +106,7 @@ static void __dfufunc udp_ep0_send_stall(void)
 
 static u_int8_t status;
 static u_int8_t *ptr;
-static u_int8_t dfu_state;
+static __dfudata u_int32_t dfu_state;
 
 static int __dfufunc handle_dnload(u_int16_t val, u_int16_t len)
 {
@@ -149,7 +148,7 @@ static __dfufunc int handle_upload(u_int16_t val, u_int16_t len)
 {
 	DEBUGE("upload ");
 	if (len > AT91C_IFLASH_PAGE_SIZE
-	    || ptr > AT91C_IFLASH_SIZE) {
+	    || ptr > AT91C_IFLASH_SIZE - 0x1000) {
 		/* Too big */
 		dfu_state = DFU_STATE_dfuERROR;
 		status = DFU_STATUS_errADDRESS;
@@ -226,7 +225,7 @@ int __dfufunc dfu_ep0_handler(u_int8_t req_type, u_int8_t req,
 			handle_dnload(val, len);
 			break;
 		case USB_REQ_DFU_UPLOAD:
-			ptr = 0;
+			ptr = 0x00101000; /* Flash base address for app */
 			dfu_state = DFU_STATE_dfuUPLOAD_IDLE;
 			handle_upload(val, len);
 			break;
@@ -667,6 +666,7 @@ void __dfufunc dfu_main(void)
 }
 
 const struct dfuapi __dfufunctab dfu_api = {
+	.udp_init		= &udp_init,
 	.ep0_send_data		= &udp_ep0_send_data,
 	.ep0_send_zlp		= &udp_ep0_send_zlp,
 	.ep0_send_stall		= &udp_ep0_send_stall,
diff --git a/firmware/src/os/dfu.h b/firmware/src/dfu/dfu.h
index 8786044..992a4f2 100644
--- a/firmware/src/os/dfu.h
+++ b/firmware/src/dfu/dfu.h
@@ -13,8 +13,6 @@
 #include <usb_ch9.h>
 #include <usb_dfu.h>
 
-#include "dbgu.h"
-
 /* USB DFU functional descriptor */
 #define DFU_FUNC_DESC  {						\
 	.bLength		= USB_DT_DFU_SIZE,			\
@@ -38,9 +36,10 @@
 	.iInterface		= 1,					\
 }
 
-#define __dfufunc __attribute__ ((long_call, section (".dfu.func")))
-#define __dfustruct __attribute__ ((section (".dfu.struct"))) const
 #define __dfufunctab  __attribute__ ((section (".dfu.functab")))
+#define __dfudata __attribute__ ((section (".data.shared")))
+#define __dfufunc 
+#define __dfustruct const
 	
 #if 0
 extern void __dfufunc udp_ep0_send_data(const char *data, u_int32_t length);
@@ -55,9 +54,6 @@ extern static u_int8_t dfu_state;
 struct udp_pcd;
 #endif
 
-
-extern void __dfufunc udp_init(void);
-
 struct _dfu_desc {
 	struct usb_config_descriptor ucfg;
 	struct usb_interface_descriptor uif[2];
@@ -65,6 +61,7 @@ struct _dfu_desc {
 };
 
 struct dfuapi {
+	void (*udp_init)(void);
 	void (*ep0_send_data)(const char *data, u_int32_t len);
 	void (*ep0_send_zlp)(void);
 	void (*ep0_send_stall)(void);
diff --git a/firmware/src/os/main.c b/firmware/src/os/main.c
index 4b7a7a2..878fdbf 100644
--- a/firmware/src/os/main.c
+++ b/firmware/src/os/main.c
@@ -3,7 +3,6 @@
 #include <include/lib_AT91SAM7.h>
 #include <os/dbgu.h>
 #include <os/led.h>
-#include <os/dfu.h>
 #include <os/main.h>
 #include <os/power.h>
 #include <os/pcd_enumerate.h>
@@ -20,7 +19,6 @@ int main(void)
 	_init_func();
 
 	/* initialize USB */
-	udp_init();
 	udp_open();
 
 	// Enable User Reset and set its minimal assertion to 960 us
diff --git a/firmware/src/os/pcd_enumerate.c b/firmware/src/os/pcd_enumerate.c
index cded8c8..40bd88e 100644
--- a/firmware/src/os/pcd_enumerate.c
+++ b/firmware/src/os/pcd_enumerate.c
@@ -23,7 +23,7 @@
 
 #include <os/pcd_enumerate.h>
 #include <os/req_ctx.h>
-#include <os/dfu.h>
+#include <dfu/dfu.h>
 #include "../openpcd.h"
 #include <os/dbgu.h>
 
@@ -41,6 +41,7 @@
 #ifdef CONFIG_DFU
 #define DFU_API_LOCATION	((const struct dfuapi *) 0x00102100)
 static const struct dfuapi *dfu = DFU_API_LOCATION;
+#define udp_init		dfu->udp_init
 #define udp_ep0_send_data	dfu->ep0_send_data
 #define udp_ep0_send_zlp	dfu->ep0_send_zlp
 #define udp_ep0_send_stall	dfu->ep0_send_stall
@@ -328,6 +329,7 @@ static void udp_irq(void)
 void udp_open(void)
 {
 	DEBUGPCRF("entering");
+	udp_init();
 	upcd.pUdp = AT91C_BASE_UDP;
 	upcd.cur_config = 0;
 	upcd.cur_rcv_bank = AT91C_UDP_RX_DATA_BK0;
@@ -340,7 +342,6 @@ void udp_open(void)
 	/* End-of-Bus-Reset is always enabled */
 
 	/* Set the Pull up resistor */
-	AT91F_PIO_CfgOutput(AT91C_BASE_PIOA, OPENPCD_PIO_UDP_PUP);
 	AT91F_PIO_SetOutput(AT91C_BASE_PIOA, OPENPCD_PIO_UDP_PUP);
 }
 
diff --git a/firmware/src/os/pcd_enumerate.h b/firmware/src/os/pcd_enumerate.h
index 57ff88c..813243e 100644
--- a/firmware/src/os/pcd_enumerate.h
+++ b/firmware/src/os/pcd_enumerate.h
@@ -5,7 +5,7 @@
 #include <sys/types.h>
 #include <asm/atomic.h>
 #include "openpcd.h"
-#include "dfu.h"
+#include <dfu/dfu.h>
 
 struct req_ctx;
 
diff --git a/firmware/src/start/Cstartup.S b/firmware/src/start/Cstartup.S
index e91fd86..e7d5714 100644
--- a/firmware/src/start/Cstartup.S
+++ b/firmware/src/start/Cstartup.S
@@ -76,165 +76,22 @@
 	.text
 	.arm
 	.section	.vectram, "ax"
-resetvecR:	B	resetvecR
-undefvecR:	B	undefvecR
-swivecR:	B	swivecR
-pabtvecR:	B	pabtvecR
-dabtvecR:	B	dabtvecR
-rsvdvecR:	B	rsvdvecR
-irqvecR:	B	IRQ_Handler_EntryR
-fiqvecR:	
 
-FIQ_Handler_EntryR:
-
-/*- Switch in SVC/User Mode to allow User Stack access for C code 	*/
-/* because the FIQ is not yet acknowledged*/
-
-/*- Save and r0 in FIQ_Register */
-            mov         r9,r0
-	        ldr         r0 , [r8, #AIC_FVR]
-            msr         CPSR_c,#I_BIT | F_BIT | ARM_MODE_SVC
-
-/*- Save scratch/used registers and LR in User Stack */
-            stmfd       sp!, { r1-r3, r12, lr}
-
-/*- Branch to the routine pointed by the AIC_FVR */
-            mov         r14, pc
-            bx          r0
-
-/*- Restore scratch/used registers and LR from User Stack */
-            ldmia       sp!, { r1-r3, r12, lr}
-
-/*- Leave Interrupts disabled and switch back in FIQ mode */
-            msr         CPSR_c, #I_BIT | F_BIT | ARM_MODE_FIQ
-
-/*- Restore the R0 ARM_MODE_SVC register */
-            mov         r0,r9
-
-/*- Restore the Program Counter using the LR_fiq directly in the PC */
-            subs        pc,lr,#4
-
-        .global IRQ_Handler_EntryR
-        .func   IRQ_Handler_EntryR
-
-IRQ_Handler_EntryR:
-
-/*- Manage Exception Entry  */
-/*- Adjust and save LR_irq in IRQ stack  */
-            sub         lr, lr, #4
-            stmfd       sp!, {lr}
-
-/*- Save SPSR need to be saved for nested interrupt */
-            mrs         r14, SPSR
-            stmfd       sp!, {r14}
-
-/*- Save and r0 in IRQ stack  */
-            stmfd       sp!, {r0}
-
-/*- Write in the IVR to support Protect Mode  */
-/*- No effect in Normal Mode  */
-/*- De-assert the NIRQ and clear the source in Protect Mode */
-            ldr         r14, =AT91C_BASE_AIC
-	    ldr         r0 , [r14, #AIC_IVR]
-	    str         r14, [r14, #AIC_IVR]
-
-/*- Enable Interrupt and Switch in Supervisor Mode */
-            msr         CPSR_c, #ARM_MODE_SVC
-
-/*- Save scratch/used registers and LR in User Stack */
-            stmfd       sp!, { r1-r3, r12, r14}
-
-/*- Branch to the routine pointed by the AIC_IVR  */
-            mov         r14, pc
-            bx          r0
-/*- Restore scratch/used registers and LR from User Stack*/
-            ldmia       sp!, { r1-r3, r12, r14}
-
-/*- Disable Interrupt and switch back in IRQ mode */
-            msr         CPSR_c, #I_BIT | ARM_MODE_IRQ
-
-/*- Mark the End of Interrupt on the AIC */
-            ldr         r14, =AT91C_BASE_AIC
-            str         r14, [r14, #AIC_EOICR]
-
-/*- Restore SPSR_irq and r0 from IRQ stack */
-            ldmia       sp!, {r0}
-
-/*- Restore SPSR_irq and r0 from IRQ stack */
-            ldmia       sp!, {r14}
-            msr         SPSR_cxsf, r14
-
-/*- Restore adjusted  LR_irq from IRQ stack directly in the PC */
-            ldmia       sp!, {pc}^
-	
-        .size   IRQ_Handler_EntryR, . - IRQ_Handler_EntryR
-        .endfunc
-
-	.global remap
-	.func	remap
-_remap:
-#		led1on
-# Remap RAM to 0x00000000 for DFU 
+	.global _remap_call_dfu
+	.func	_remap_call_dfu
+_remap_call_dfu:
+		led1on
+		/* Remap RAM to 0x00000000 for DFU */
 		ldr	r1, =AT91C_BASE_AIC
 		mov	r2, #0x01
 		str	r2, [r1, #AIC_MCR_RCR]
+		
+		ldr	r4, =dfu_main
+		bx	r4
 
-		/* prepare c function call to main */
-		mov	r0, #0	/* argc = 0 */
-		ldr	lr,=exit
-		ldr	r10,=main
-
-#ifdef CONFIG_DFU_SWITCH
-		/* check whether bootloader button is pressed */
-		ldr	r1, =AT91C_PMC_PCER
-		mov	r2, #(1 << AT91C_ID_PIOA)
-		str	r2, [r1] 
-
-		ldr 	r1, =AT91C_BASE_PIOA
-		ldr	r2, [r1, #PIOA_PDSR]
-		tst	r2, #PIO_BOOTLDR
-		ldrne	r10,=dfu_main
-#endif
-
-		bx	r10
-	.size	remap, . - remap
+	.size	_remap_call_dfu, . - _remap_call_dfu
 	.endfunc
 
-/* "exit" dummy added by mthomas to avoid sbrk write read etc. needed
-   by the newlib default "exit" */
-        .global exit
-        .func   exit
-exit:
-        b    .
-		.size   exit, . - exit
-        .endfunc
-
-/*---------------------------------------------------------------
-//* ?EXEPTION_VECTOR
-//* This module is only linked if needed for closing files.
-//*---------------------------------------------------------------*/
-        .global AT91F_Default_FIQ_handler
-        .func   AT91F_Default_FIQ_handler
-AT91F_Default_FIQ_handler:
-            b     AT91F_Default_FIQ_handler
-        .size   AT91F_Default_FIQ_handler, . - AT91F_Default_FIQ_handler
-        .endfunc
-
-        .global AT91F_Default_IRQ_handler
-        .func   AT91F_Default_IRQ_handler
-AT91F_Default_IRQ_handler:
-            b     AT91F_Default_IRQ_handler
-        .size   AT91F_Default_IRQ_handler, . - AT91F_Default_IRQ_handler
-        .endfunc
-
-        .global AT91F_Spurious_handler
-        .func   AT91F_Spurious_handler
-AT91F_Spurious_handler:
-            b     AT91F_Spurious_handler
-        .size   AT91F_Spurious_handler, . - AT91F_Spurious_handler
-        .endfunc
-
-
 
 #;------------------------------------------------------------------------------
 #;- Section Definition
@@ -255,9 +112,6 @@ Top_Stack:
 * .text is used instead of .section .text so it works with arm-aout too.  */
         .section 	.reset
         .text
-        .global _startup
-        .func   _startup
-_startup:
 reset: 
 /*------------------------------------------------------------------------------
 //*- Exception vectors 
@@ -277,17 +131,108 @@ swivec:
 pabtvec:
                 B           pabtvec             /* 0x0C Prefetch Abort */
 dabtvec:
-                B           dabtvec             /* 0x10 Data Abort */
+		b	dabtvec             /* 0x10 Data Abort */
 rsvdvec:
-                B           rsvdvec             /* 0x14 reserved  */
+		b	rsvdvec             /* 0x14 reserved  */
 irqvec:
-                B           irqvec		/* 0x18 IRQ	 */
-fiqvec:               		  
-		B	    fiqvec          	/* 0x1c FIQ	*/
+		b	IRQ_Handler_Entry	/* 0x18 IRQ */
+fiqvec:
+		b	FIQ_Handler_Entry
+						/* 0x1c FIQ */
+dfu_state_dummy:
+		.word	0
+		
+FIQ_Handler_Entry:
+
+/*- Switch in SVC/User Mode to allow User Stack access for C code 	*/
+/* because the FIQ is not yet acknowledged*/
+
+/*- Save and r0 in FIQ_Register */
+		mov	r9, r0
+		ldr	r0, [r8, #AIC_FVR]
+		msr	CPSR_c, #I_BIT | F_BIT | ARM_MODE_SVC
+
+		/*- Save scratch/used registers and LR in User Stack */
+		stmfd	sp!, { r1-r3, r12, lr}
+
+		/*- Branch to the routine pointed by the AIC_FVR */
+		mov	r14, pc
+		bx	r0
+
+		/*- Restore scratch/used registers and LR from User Stack */
+		ldmia	sp!, { r1-r3, r12, lr}
+
+		/*- Leave Interrupts disabled and switch back in FIQ mode */
+		msr	CPSR_c, #I_BIT | F_BIT | ARM_MODE_FIQ
+
+		/*- Restore the R0 ARM_MODE_SVC register */
+		mov	r0,r9
+
+		/*- Restore the Program Counter using the LR_fiq directly in the PC */
+		subs        pc, lr, #4
+
+	.global IRQ_Handler_Entry
+	.func   IRQ_Handler_Entry
+
+IRQ_Handler_Entry:
+
+		/*- Manage Exception Entry  */
+		/*- Adjust and save LR_irq in IRQ stack  */
+		sub         lr, lr, #4
+		stmfd       sp!, {lr}
+
+		/*- Save SPSR need to be saved for nested interrupt */
+		mrs	r14, SPSR
+		stmfd	sp!, {r14}
+
+		/*- Save and r0 in IRQ stack  */
+		stmfd	sp!, {r0}
+
+		/*- Write in the IVR to support Protect Mode  */
+		/*- No effect in Normal Mode  */
+		/*- De-assert the NIRQ and clear the source in Protect Mode */
+		ldr	r14, =AT91C_BASE_AIC
+		ldr	r0 , [r14, #AIC_IVR]
+		str	r14, [r14, #AIC_IVR]
+
+		/*- Enable Interrupt and Switch in Supervisor Mode */
+		msr	CPSR_c, #ARM_MODE_SVC
+
+		/*- Save scratch/used registers and LR in User Stack */
+		stmfd	sp!, { r1-r3, r12, r14}
+
+		/*- Branch to the routine pointed by the AIC_IVR  */
+		mov	r14, pc
+		bx	r0
+
+		/*- Restore scratch/used registers and LR from User Stack*/
+		ldmia	sp!, { r1-r3, r12, r14}
+
+		/*- Disable Interrupt and switch back in IRQ mode */
+		msr	CPSR_c, #I_BIT | ARM_MODE_IRQ
+
+		/*- Mark the End of Interrupt on the AIC */
+		ldr	r14, =AT91C_BASE_AIC
+		str	r14, [r14, #AIC_EOICR]
+
+		/*- Restore SPSR_irq and r0 from IRQ stack */
+		ldmia	sp!, {r0}
+
+		/*- Restore SPSR_irq and r0 from IRQ stack */
+		ldmia	sp!, {r14}
+		msr	SPSR_cxsf, r14
+
+		/*- Restore adjusted  LR_irq from IRQ stack directly in the PC */
+		ldmia	sp!, {pc}^
+
+	.size   IRQ_Handler_Entry, . - IRQ_Handler_Entry
+	.endfunc
 	.align 0
 .RAM_TOP:
 	.word	Top_Stack
 
+	.global _startup
+	.func _startup
 InitReset:
 /*------------------------------------------------------------------------------
 /*- Low level Init (PMC, AIC, ? ....) by C function AT91F_LowLevelInit
@@ -348,16 +293,7 @@ InitReset:
                 msr     CPSR_c, #ARM_MODE_SVC
                 mov     r13, r0                     /* Init stack Sup */
 
-/*- Relocate DFU .data section (Copy from ROM to RAM)*/
-		ldr	r1, =_etext_dfu
-		ldr	r2, =_data_dfu
-		ldr	r3, =_edata_dfu
-LoopRelDFU:	cmp	r2, r3
-		ldrlo	r0, [r1], #4
-		strlo	r0, [r2], #4
-                blo	LoopRelDFU
-
-# Relocate .data section (Copy from ROM to RAM)
+# Relocate DFU .data section (Copy from ROM to RAM)
                 LDR     R1, =_etext
                 LDR     R2, =_data
                 LDR     R3, =_edata
@@ -366,7 +302,7 @@ LoopRel:        CMP     R2, R3
                 STRLO   R0, [R2], #4
                 BLO     LoopRel
 
-# Clear .bss section (Zero init)
+# Clear DFU .bss section (Zero init)
                 MOV     R0, #0
                 LDR     R1, =__bss_start__
                 LDR     R2, =__bss_end__
@@ -374,13 +310,75 @@ LoopZI:         CMP     R1, R2
                 STRLO   R0, [R1], #4
                 BLO     LoopZI
 
-		led1on
+		/* prepare c function call to main */
+		mov	r0, #0	/* argc = 0 */
+		ldr	lr, =exit
+		ldr	r10, =0x00101000
 
-		ldr	r0, =_remap
-		bx	r0
+#ifdef CONFIG_DFU_SWITCH
+		/* check whether bootloader button is pressed */
+		ldr	r1, =AT91C_PMC_PCER
+		mov	r2, #(1 << AT91C_ID_PIOA)
+		str	r2, [r1] 
 
+		ldr 	r1, =AT91C_BASE_PIOA
+		ldr	r2, [r1, #PIOA_PDSR]
+		tst	r2, #PIO_BOOTLDR
+		bne	_reloc_dfu_text
+#endif
+
+		bx	r10
+
+_reloc_dfu_text:
+
+		ldr	r1, =0x00100000
+		ldr	r2, =0x00200000
+		ldr	r3, =_etext
+		add	r3, r3, r2
+loop_rel_t:	cmp	r2, r3
+		ldrlo	r4, [r1], #4
+		strlo	r4, [r2], #4
+		blo	loop_rel_t
+		ldr	r4, =_remap_call_dfu
+		bx	r4
+		
         .size   _startup, . - _startup
         .endfunc
-		
+
+/* "exit" dummy to avoid sbrk write read etc. needed by the newlib default "exit" */
+        .global exit
+        .func   exit
+exit:
+        b    .
+		.size   exit, . - exit
+        .endfunc
+
+/*---------------------------------------------------------------
+//* ?EXEPTION_VECTOR
+//* This module is only linked if needed for closing files.
+//*---------------------------------------------------------------*/
+        .global AT91F_Default_FIQ_handler
+        .func   AT91F_Default_FIQ_handler
+AT91F_Default_FIQ_handler:
+            b     AT91F_Default_FIQ_handler
+        .size   AT91F_Default_FIQ_handler, . - AT91F_Default_FIQ_handler
+        .endfunc
+
+        .global AT91F_Default_IRQ_handler
+        .func   AT91F_Default_IRQ_handler
+AT91F_Default_IRQ_handler:
+            b     AT91F_Default_IRQ_handler
+        .size   AT91F_Default_IRQ_handler, . - AT91F_Default_IRQ_handler
+        .endfunc
+
+        .global AT91F_Spurious_handler
+        .func   AT91F_Spurious_handler
+AT91F_Spurious_handler:
+            b     AT91F_Spurious_handler
+        .size   AT91F_Spurious_handler, . - AT91F_Spurious_handler
+        .endfunc
+
+
+
         .end
 
diff --git a/firmware/src/start/Cstartup_app.S b/firmware/src/start/Cstartup_app.S
new file mode 100644
index 0000000..4a2187a
--- /dev/null
+++ b/firmware/src/start/Cstartup_app.S
@@ -0,0 +1,81 @@
+/* Cstartup header for the application to be started by at91dfu 
+ * (C) 2006 by Harald Welte <hwelte@hmw-consulting.de> */
+
+//#define DEBUG_LL
+
+#ifdef DEBUG_LL
+/* Debugging macros for switching on/off LED1 (green) */
+#define PIOA_PER	0xFFFFF400
+#define PIOA_OER	0xFFFFF410
+#define PIOA_SODR	0xFFFFF430
+#define PIOA_CODR	0xFFFFF434
+#define LED1		25		/* this only works on OpenPICC, not Olimex */
+	.macro	led1on
+		ldr	r2, =PIOA_CODR
+		mov	r1, #(1 << LED1)
+		str	r1, [r2]
+	.endm
+	.macro	led1off
+		ldr	r2, =PIOA_SODR
+		mov	r1, #(1 << LED1)
+		str	r1, [r2]
+	.endm
+	.macro	ledinit
+		ldr	r2, =PIOA_PER
+		mov	r1, #(1 << LED1)
+		str	r1, [r2]
+		ldr	r2, =PIOA_OER
+		str	r1, [r2]
+		led1off
+	.endm
+#else
+	.macro ledinit
+	.endm
+	.macro led1on
+	.endm
+	.macro led1off
+	.endm
+#endif
+
+	.global	_startup
+	.func _startup
+_startup:
+	/* Relocate .data section (copy from Flash to RAM) */
+	ldr	r1, =_etext
+	ldr	r2, =_data
+	ldr	r3, =_edata
+loop_r:	cmp	r2, r3
+	ldrlo	r0, [r1], #4
+	strlo	r0, [r2], #4
+	blo	loop_r
+
+	/* Clear .bss section (Zero init) */
+	mov	r0, #0
+	ldr	r1, =__bss_start__
+	ldr	r2, =__bss_end__
+loop_z:	cmp	r1, r2
+	strlo	r0, [r1], #4
+	blo	loop_z
+
+	led1on
+
+	/* prepare C function call to main */
+	mov	r0, #0	/* argc = 0 */
+	ldr	lr, =exit
+	ldr	r10, =main
+
+	bx	r10
+
+        .size   _startup, . - _startup
+        .endfunc
+		
+/* "exit" dummy to avoid sbrk write read etc. needed by the newlib default "exit" */
+        .global exit
+        .func   exit
+exit:
+        b    .
+		.size   exit, . - exit
+        .endfunc
+
+        .end
+