final_practice

Week15_Practice/Makefile

+CROSS_COMPILE ?= arm-none-eabi-
+CC := $(CROSS_COMPILE)gcc
+CFLAGS = -fno-common -O0 -std=gnu99 \
+	-mcpu=cortex-m3 -mthumb \
+	-T countdown.ld -nostartfiles -g \
+
+TARGET = countdown.bin
+all: $(TARGET)
+
+$(TARGET): countdown.c startup.c
+	$(CC) $(CFLAGS) $^ -o countdown.elf
+	$(CROSS_COMPILE)objcopy -Obinary countdown.elf countdown.bin
+	$(CROSS_COMPILE)objdump -S countdown.elf > countdown.list
+
+qemu: $(TARGET)
+	@qemu-system-arm -M ? | grep lm3s811evb >/dev/null || exit
+	@echo "Press Ctrl-A and then X to exit QEMU"
+	@echo
+	qemu-system-arm -M lm3s811evb -semihosting -nographic -kernel countdown.bin
+
+gdb: $(TARGET)
+	@qemu-system-arm -M ? | grep lm3s811evb >/dev/null || exit
+	@echo "Press Ctrl-A and then X to exit QEMU"
+	@echo
+	qemu-system-arm -M lm3s811evb -s -S -semihosting -nographic -kernel countdown.bin
+
+clean:
+	rm -f *.o *.bin *.elf *.list

Week15_Practice/countdown.c

+#include <stdint.h>
+#include "reg.h"
+
+static int semihost_call(int service, void *opaque){
+	register int r0 asm("r0") = service;
+	register void *r1 asm("r1") = opaque;
+	register int result asm("r0");
+	asm volatile("bkpt 0xab"
+			: "=r" (result) : "r" (r0), "r" (r1));
+	return result;
+}
+
+enum SEMIHOST_SVC {
+	SYS_WRITE = 0x05,
+};
+
+void main(void){
+	/* SysTick configuration */
+	*SYSTICK_LOAD = 5000000;
+	*SYSTICK_VAL = 0;
+	*SYSTICK_CTRL = 0x07;
+
+	while(1);
+}
+
+int systick_handler(void){
+	char seconds[] = {'5','4','3','2','1','0'};
+	static int counts = 5;
+	uint32_t param[] = {1, (uint32_t)&seconds[counts], 1};
+	semihost_call(SYS_WRITE, (void*) param);
+	counts = counts < 0 ? 5 : counts - 1;
+}

Week15_Practice/countdown.ld

+ENTRY(reset_handler)
+
+MEMORY{
+	FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 64K
+	RAM (rwx) : ORIGIN = 0x20000000, LENGTH = 8K
+}
+
+SECTIONS
+{
+	.text : {
+		KEEP(*(.isr_vector))
+		*(.text)
+		*(.text.*)
+		*(.rodata)
+		_sidata = .;
+	} >FLASH
+
+	.data : AT(_sidata){
+		_sdata = .;
+		*(.data)
+		*(.data*)
+		_edata = .;
+	} >RAM
+
+	.bss : {
+		_sbss = .;
+		*(.bss)
+		_ebss = .;
+	} >RAM
+
+	_estack = ORIGIN(RAM) + LENGTH(RAM);
+}

Week15_Practice/countdown.list

+
+countdown.elf:     file format elf32-littlearm
+
+
+Disassembly of section .text:
+
+00000000 <isr_vectors>:
+   0:	00 20 00 20 e1 00 00 00 49 01 00 00 49 01 00 00     . . ....I...I...
+  10:	49 01 00 00 49 01 00 00 49 01 00 00 00 00 00 00     I...I...I.......
+	...
+  2c:	49 01 00 00 00 00 00 00 00 00 00 00 49 01 00 00     I...........I...
+  3c:	85 00 00 00                                         ....
+
+00000040 <semihost_call>:
+#include <stdint.h>
+#include "reg.h"
+
+static int semihost_call(int service, void *opaque){
+  40:	b480      	push	{r7}
+  42:	b083      	sub	sp, #12
+  44:	af00      	add	r7, sp, #0
+  46:	6078      	str	r0, [r7, #4]
+  48:	6039      	str	r1, [r7, #0]
+	register int r0 asm("r0") = service;
+  4a:	6878      	ldr	r0, [r7, #4]
+	register void *r1 asm("r1") = opaque;
+  4c:	6839      	ldr	r1, [r7, #0]
+	register int result asm("r0");
+	asm volatile("bkpt 0xab"
+  4e:	beab      	bkpt	0x00ab
+			: "=r" (result) : "r" (r0), "r" (r1));
+	return result;
+  50:	4603      	mov	r3, r0
+}
+  52:	4618      	mov	r0, r3
+  54:	370c      	adds	r7, #12
+  56:	46bd      	mov	sp, r7
+  58:	bc80      	pop	{r7}
+  5a:	4770      	bx	lr
+
+0000005c <main>:
+
+enum SEMIHOST_SVC {
+	SYS_WRITE = 0x05,
+};
+
+void main(void){
+  5c:	b480      	push	{r7}
+  5e:	af00      	add	r7, sp, #0
+	/* SysTick configuration */
+	*SYSTICK_LOAD = 5000000;
+  60:	4b04      	ldr	r3, [pc, #16]	; (74 <main+0x18>)
+  62:	4a05      	ldr	r2, [pc, #20]	; (78 <main+0x1c>)
+  64:	601a      	str	r2, [r3, #0]
+	*SYSTICK_VAL = 0;
+  66:	4b05      	ldr	r3, [pc, #20]	; (7c <main+0x20>)
+  68:	2200      	movs	r2, #0
+  6a:	601a      	str	r2, [r3, #0]
+	*SYSTICK_CTRL = 0x07;
+  6c:	4b04      	ldr	r3, [pc, #16]	; (80 <main+0x24>)
+  6e:	2207      	movs	r2, #7
+  70:	601a      	str	r2, [r3, #0]
+
+	while(1);
+  72:	e7fe      	b.n	72 <main+0x16>
+  74:	e000e014 	.word	0xe000e014
+  78:	004c4b40 	.word	0x004c4b40
+  7c:	e000e018 	.word	0xe000e018
+  80:	e000e010 	.word	0xe000e010
+
+00000084 <systick_handler>:
+}
+
+int systick_handler(void){
+  84:	b580      	push	{r7, lr}
+  86:	b086      	sub	sp, #24
+  88:	af00      	add	r7, sp, #0
+	char seconds[] = {'5','4','3','2','1','0'};
+  8a:	4a13      	ldr	r2, [pc, #76]	; (d8 <systick_handler+0x54>)
+  8c:	f107 0310 	add.w	r3, r7, #16
+  90:	e892 0003 	ldmia.w	r2, {r0, r1}
+  94:	6018      	str	r0, [r3, #0]
+  96:	3304      	adds	r3, #4
+  98:	8019      	strh	r1, [r3, #0]
+	static int counts = 5;
+	uint32_t param[] = {1, (uint32_t)&seconds[counts], 1};
+  9a:	2301      	movs	r3, #1
+  9c:	607b      	str	r3, [r7, #4]
+  9e:	4b0f      	ldr	r3, [pc, #60]	; (dc <systick_handler+0x58>)
+  a0:	681b      	ldr	r3, [r3, #0]
+  a2:	f107 0210 	add.w	r2, r7, #16
+  a6:	4413      	add	r3, r2
+  a8:	60bb      	str	r3, [r7, #8]
+  aa:	2301      	movs	r3, #1
+  ac:	60fb      	str	r3, [r7, #12]
+	semihost_call(SYS_WRITE, (void*) param);
+  ae:	1d3b      	adds	r3, r7, #4
+  b0:	4619      	mov	r1, r3
+  b2:	2005      	movs	r0, #5
+  b4:	f7ff ffc4 	bl	40 <semihost_call>
+	counts = counts < 0 ? 5 : counts - 1;
+  b8:	4b08      	ldr	r3, [pc, #32]	; (dc <systick_handler+0x58>)
+  ba:	681b      	ldr	r3, [r3, #0]
+  bc:	2b00      	cmp	r3, #0
+  be:	db03      	blt.n	c8 <systick_handler+0x44>
+  c0:	4b06      	ldr	r3, [pc, #24]	; (dc <systick_handler+0x58>)
+  c2:	681b      	ldr	r3, [r3, #0]
+  c4:	3b01      	subs	r3, #1
+  c6:	e000      	b.n	ca <systick_handler+0x46>
+  c8:	2305      	movs	r3, #5
+  ca:	4a04      	ldr	r2, [pc, #16]	; (dc <systick_handler+0x58>)
+  cc:	6013      	str	r3, [r2, #0]
+}
+  ce:	bf00      	nop
+  d0:	4618      	mov	r0, r3
+  d2:	3718      	adds	r7, #24
+  d4:	46bd      	mov	sp, r7
+  d6:	bd80      	pop	{r7, pc}
+  d8:	00000150 	.word	0x00000150
+  dc:	20000000 	.word	0x20000000
+
+000000e0 <reset_handler>:
+extern uint32_t _sbss;
+extern uint32_t _ebss;
+
+extern void main(void);
+void reset_handler(void)
+{
+  e0:	b580      	push	{r7, lr}
+  e2:	b086      	sub	sp, #24
+  e4:	af00      	add	r7, sp, #0
+	/* Copy the data segment initializers from flash to SRAM */
+	uint32_t *idata_begin = &_sidata;
+  e6:	4b13      	ldr	r3, [pc, #76]	; (134 <reset_handler+0x54>)
+  e8:	617b      	str	r3, [r7, #20]
+	uint32_t *data_begin = &_sdata;
+  ea:	4b13      	ldr	r3, [pc, #76]	; (138 <reset_handler+0x58>)
+  ec:	613b      	str	r3, [r7, #16]
+	uint32_t *data_end = &_edata;
+  ee:	4b13      	ldr	r3, [pc, #76]	; (13c <reset_handler+0x5c>)
+  f0:	60bb      	str	r3, [r7, #8]
+	while(data_begin < data_end) *data_begin++ = *idata_begin++;
+  f2:	e007      	b.n	104 <reset_handler+0x24>
+  f4:	693b      	ldr	r3, [r7, #16]
+  f6:	1d1a      	adds	r2, r3, #4
+  f8:	613a      	str	r2, [r7, #16]
+  fa:	697a      	ldr	r2, [r7, #20]
+  fc:	1d11      	adds	r1, r2, #4
+  fe:	6179      	str	r1, [r7, #20]
+ 100:	6812      	ldr	r2, [r2, #0]
+ 102:	601a      	str	r2, [r3, #0]
+ 104:	693a      	ldr	r2, [r7, #16]
+ 106:	68bb      	ldr	r3, [r7, #8]
+ 108:	429a      	cmp	r2, r3
+ 10a:	d3f3      	bcc.n	f4 <reset_handler+0x14>
+
+	/* Zero fill the bss segment */
+	uint32_t *bss_begin = &_sbss;
+ 10c:	4b0c      	ldr	r3, [pc, #48]	; (140 <reset_handler+0x60>)
+ 10e:	60fb      	str	r3, [r7, #12]
+	uint32_t *bss_end = &_ebss;
+ 110:	4b0c      	ldr	r3, [pc, #48]	; (144 <reset_handler+0x64>)
+ 112:	607b      	str	r3, [r7, #4]
+	while(bss_begin < bss_end) *bss_begin++ = 0;
+ 114:	e004      	b.n	120 <reset_handler+0x40>
+ 116:	68fb      	ldr	r3, [r7, #12]
+ 118:	1d1a      	adds	r2, r3, #4
+ 11a:	60fa      	str	r2, [r7, #12]
+ 11c:	2200      	movs	r2, #0
+ 11e:	601a      	str	r2, [r3, #0]
+ 120:	68fa      	ldr	r2, [r7, #12]
+ 122:	687b      	ldr	r3, [r7, #4]
+ 124:	429a      	cmp	r2, r3
+ 126:	d3f6      	bcc.n	116 <reset_handler+0x36>
+
+	/* jump to C entry point */
+    main();
+ 128:	f7ff ff98 	bl	5c <main>
+}
+ 12c:	bf00      	nop
+ 12e:	3718      	adds	r7, #24
+ 130:	46bd      	mov	sp, r7
+ 132:	bd80      	pop	{r7, pc}
+ 134:	00000156 	.word	0x00000156
+ 138:	20000000 	.word	0x20000000
+ 13c:	20000004 	.word	0x20000004
+ 140:	20000004 	.word	0x20000004
+ 144:	20000004 	.word	0x20000004
+
+00000148 <default_handler>:
+
+void default_handler(void){
+ 148:	b480      	push	{r7}
+ 14a:	af00      	add	r7, sp, #0
+	while(1);
+ 14c:	e7fe      	b.n	14c <default_handler+0x4>
+ 14e:	bf00      	nop
+ 150:	32333435 	.word	0x32333435
+ 154:	3031      	.short	0x3031

Week15_Practice/reg.h

+#ifndef __REG_H__
+#define __REG_H__
+
+#define __REG_TYPE     volatile uint32_t
+#define __REG          __REG_TYPE *
+
+/* SysTick Memory Map */
+#define SYSTICK        ((__REG_TYPE) 0xE000E010)
+#define SYSTICK_CTRL   ((__REG) (SYSTICK + 0x00))
+#define SYSTICK_LOAD   ((__REG) (SYSTICK + 0x04))
+#define SYSTICK_VAL    ((__REG) (SYSTICK + 0x08))
+
+#endif
+
+

Week15_Practice/semi.c

+#include <stdint.h>
+
+static int semihost_call(int service, void* opaque)
+{
+    register int r0 asm("r0") = service;
+    register void *r1 asm("r1") = opaque;
+    register int result asm("r0");
+    asm volatile("bkpt 0xab" : "=r" (result) : "r" (r0), "r" (r1));
+    return result;
+}
+
+enum SEMIHOST_SVC{
+    SYS_WRITE = 0x05,
+};
+
+char g_message[] = "Hello World!\n";
+uint32_t g_param[3];
+
+void main(void)
+{
+	g_param[0] = 1;
+	g_param[1] = g_message;
+	g_param[2] = sizeof(g_message);
+    //char message[] = "Hello World!\n";
+    //uint32_t param[] = {1, (uint32_t)g_message, sizeof(g_message)};
+    semihost_call(SYS_WRITE, (void*)g_param);
+    while(1);
+}

Week15_Practice/semi.ld

+ENTRY(reset_handler)
+
+MEMORY
+{
+    FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 64K
+	RAM (rwx) : ORIGIN = 0x20000000, LENGTH = 8k
+}
+
+SECTIONS
+{
+    .text :
+    {
+        KEEP(*(.isr_vector))
+        *(.text)
+		*(.text.*)
+		*(.rodata)
+		_sidata = .;
+
+    } >FLASH
+
+	.data : AT(_sidata){
+		_sdata = .;
+		*(.data)
+		*(.data*)
+		_edata = .;
+	} >RAM
+
+	.bss : {
+		_sbss = .;
+		*(.bss)
+		_ebss = .;
+	} >RAM
+
+	_estack = ORIGIN(RAM) + LENGTH(RAM);
+}

Week15_Practice/startup.c

+#include <stdint.h>
+
+extern uint32_t _estack;
+extern uint32_t _sidata;
+extern uint32_t _sdata;
+extern uint32_t _edata;
+extern uint32_t _sbss;
+extern uint32_t _ebss;
+
+extern void main(void);
+void reset_handler(void)
+{
+	/* Copy the data segment initializers from flash to SRAM */
+	uint32_t *idata_begin = &_sidata;
+	uint32_t *data_begin = &_sdata;
+	uint32_t *data_end = &_edata;
+	while(data_begin < data_end) *data_begin++ = *idata_begin++;
+
+	/* Zero fill the bss segment */
+	uint32_t *bss_begin = &_sbss;
+	uint32_t *bss_end = &_ebss;
+	while(bss_begin < bss_end) *bss_begin++ = 0;
+
+	/* jump to C entry point */
+    main();
+}
+
+void default_handler(void){
+	while(1);
+}
+
+void nmi_handler(void) __attribute((weak,alias("default_handler")));
+void hardfault_handler(void) __attribute((weak,alias("default_handler")));
+void memmanage_handler(void) __attribute((weak,alias("default_handler")));
+void busfault_handler(void) __attribute((weak,alias("default_handler")));
+void usagefault_handler(void) __attribute((weak,alias("default_handler")));
+void svc_handler(void) __attribute((weak,alias("default_handler")));
+void pendsv_handler(void) __attribute((weak,alias("default_handler")));
+void systick_handler(void) __attribute((weak,alias("default_handler")));
+
+__attribute((section(".isr_vector")))
+uint32_t *isr_vectors[] = {
+    (uint32_t*) &_estack,
+    (uint32_t*) reset_handler, /* code entry point */
+	(uint32_t*) nmi_handler,   /* NMI handler */
+	(uint32_t*) hardfault_handler, /* hard fault handler */
+	(uint32_t*) memmanage_handler, /* mem manage handler */
+	(uint32_t*) busfault_handler,  /* bus fault handler */
+	(uint32_t*) usagefault_handler, /* usage fault handler */
+	0,
+	0,
+	0,
+	0,
+	(uint32_t*) svc_handler, /* svc handler */
+	0,
+	0,
+	(uint32_t*) pendsv_handler, /* pendsv handler */
+	(uint32_t*) systick_handler, /* systick handler */
+};