• ARM裸板调试之串口打印及栈初步分析

    前面介绍的点灯调试法提供的信息并不多，接下来我们看串口调试方法，先看一下结构

    然后我们仍然用之前的nandflash来实验，nandflash前面一块代码不是用位置无关码写的，运行时会报错，我们用串口调试下。

    1 编写打印代码

    正常需要自己写串口相关代码，这里直接把之前串口实验的代码复制过来，这里注意一个问题，由于我们head.S前面的代码还没有把时钟提高到50MHz,所以这里波特率不能支持到115200，只能到57600，

    1. #define TXD0READY   (1<<2)
    2. #define RXD0READY   (1)
    3.  
    4. #define PCLK            12000000
    5. #define UART_CLK        PCLK        //  UART0的时钟源设为PCLK
    6. #define UART_BAUD_RATE  57600      // 波特率
    7. #define UART_BRD        ((UART_CLK  / (UART_BAUD_RATE * 16)) - 1)
    8.  
    9. /*
    10.  * 初始化UART0
    11.  * 57600,8N1,无流控
    12.  */
    13. void uart0_init(void)
    14. {
    15.     GPHCON  |= 0xa0;    // GPH2,GPH3用作TXD0,RXD0
    16.     GPHUP   = 0x0c;     // GPH2,GPH3内部上拉
    17.  
    18.     ULCON0  = 0x03;     // 8N1(8个数据位，无较验，1个停止位)
    19.     UCON0   = 0x05;     // 查询方式，UART时钟源为PCLK
    20.     UFCON0  = 0x00;     // 不使用FIFO
    21.     UMCON0  = 0x00;     // 不使用流控
    22.     UBRDIV0 = UART_BRD; // 波特率为115200
    23. }
    24.  
    25. /*
    26.  * 发送一个字符
    27.  */
    28. void putc(unsigned char c)
    29. {
    30.     /* 等待，直到发送缓冲区中的数据已经全部发送出去 */
    31.     while (!(UTRSTAT0 & TXD0READY));
    32.     
    33.     /* 向UTXH0寄存器中写入数据，UART即自动将它发送出去 */
    34.     UTXH0 = c;
    35. }
    36.  
    37. void puts(char *s)
    38. {
    39. 	int i = 0;
    40. 	while (s[i])
    41. 	{
    42. 		putc(s[i]);
    43. 		i++;
    44. 	}
    45. }
    46.  
    47. void puthex(unsigned long val)
    48. {
    49. 	/* val = 0x1234ABCD */
    50. 	unsigned char c;
    51. 	int i = 0;
    52. 	
    53. 	putc('0');
    54. 	putc('x');
    55.  
    56. 	for (i = 0; i < 8; i++)
    57. 	{
    58. 		c = (val >> ((7-i)*4)) & 0xf;
    59. 		if ((c >= 0) && (c <= 9))
    60. 		{
    61. 			c = '0' + c;
    62. 		}
    63. 		else if ((c >= 0xA) && (c <= 0xF))
    64. 		{
    65. 			c = 'A' + (c -  0xA);
    66. 		}
    67. 		putc(c);
    68. 	}
    69. }

    然后我们就可以在head.S中使用putc函数进行打印了，汇编调用C语言函数的时候，第一个参数是保存在r0里面的，

     打印出来发现输出的是mnm，多输出了一个m,说明程序已经跑飞了，我们再加一行打印，

     正常应该会输出mnro，结果还是输出mnm，说明输出完n之后，程序就重启了，那错误可能就在nand_init或者memsetup这两个函数里面，那我们先把nand_init注释掉，

    注释掉之后发现打印出来mnrm，那我们现在直接在memsetup里面增加打印，

     然后发现打印的乱七八糟的

     

     这是什么原因，还不清楚，如果打印字符串，字符串不一定保存在哪里(有可能保存在SDRAM里面，而打印的时候SDRAM还没有初始化)，继续改调试代码，改为

     然后编译下载，

    从打印看没有打印出来O，好像是 nandread那里崩溃了，(其实是memsetup这个函数，这个串口打印调试在这个错误上并不好用)，

    其实错误是在memsetup这里，假如我们怀疑memsetup函数，我们去调试memsetup函数，我们写内存，我们把K写进去再读出来，打印出来，如果还是K那么表明内存K是可写的，表明SDRAM初始化没问题，

    编译下载发现还是有K(越调试越晕，memsetup怎么没问题了。。。命名之前我们写的程序错误就在memsetup函数里面)，

    那我们继续，把SDRAM的寄存器打印出来，

     打印结果如下

     打印结果明显不是寄存器内容，这是因为访问内存mem_cfg_val的时候用的是他的内存地址，

    再改

     打印结果如下：

    那打印可能有点问题，可能puthex这个打印 函数不对。。。。。先测试下puthex

     测试发现这个puthex函数没问题，

    那么我们的打印就没问题，那&mem_cfg_val的地址是FB0(4016)，FB4, FB8，按说这个地址应该是链接地址才对，为什么是在前面4096里面呢，sp栈地址是4096，

    看一下反汇编吧，

    1.  
    2. nand_elf:     file format elf32-littlearm
    3.  
    4. Disassembly of section .text:
    5.  
    6. 30000000 <_start>:
    7. 30000000:	e3a0da01 	mov	sp, #4096	; 0x1000
    8. 30000004:	eb000013 	bl	30000058 <disable_watch_dog>
    9. 30000008:	eb000076 	bl	300001e8 <uart0_init>
    10. 3000000c:	e3a0006d 	mov	r0, #109	; 0x6d
    11. 30000010:	eb000014 	bl	30000068 <putc>
    12. 30000014:	eb000031 	bl	300000e0 <memsetup>
    13. 30000018:	e3a0006e 	mov	r0, #110	; 0x6e
    14. 3000001c:	eb000011 	bl	30000068 <putc>
    15. 30000020:	e3a00072 	mov	r0, #114	; 0x72
    16. 30000024:	eb00000f 	bl	30000068 <putc>
    17. 30000028:	e3a00203 	mov	r0, #805306368	; 0x30000000
    18. 3000002c:	e3a01000 	mov	r1, #0	; 0x0
    19. 30000030:	e3a02a01 	mov	r2, #4096	; 0x1000
    20. 30000034:	eb000176 	bl	30000614 <nand_read>
    21. 30000038:	e3a0006f 	mov	r0, #111	; 0x6f
    22. 3000003c:	eb000009 	bl	30000068 <putc>
    23. 30000040:	e3a0d30d 	mov	sp, #872415232	; 0x34000000
    24. 30000044:	e59fe004 	ldr	lr, [pc, #4]	; 30000050 <.text+0x50>
    25. 30000048:	e59ff004 	ldr	pc, [pc, #4]	; 30000054 <.text+0x54>
    26.  
    27. 3000004c <halt_loop>:
    28. 3000004c:	eafffffe 	b	3000004c <halt_loop>
    29. 30000050:	3000004c 	andcc	r0, r0, ip, asr #32
    30. 30000054:	30000738 	andcc	r0, r0, r8, lsr r7
    31.  
    32. 30000058 <disable_watch_dog>:
    33. 30000058:	e3a02000 	mov	r2, #0	; 0x0
    34. 3000005c:	e3a03453 	mov	r3, #1392508928	; 0x53000000
    35. 30000060:	e5832000 	str	r2, [r3]
    36. 30000064:	e1a0f00e 	mov	pc, lr
    37.  
    38. 30000068 <putc>:
    39. 30000068:	e20000ff 	and	r0, r0, #255	; 0xff
    40. 3000006c:	e3a02205 	mov	r2, #1342177280	; 0x50000000
    41. 30000070:	e5923010 	ldr	r3, [r2, #16]
    42. 30000074:	e3130004 	tst	r3, #4	; 0x4
    43. 30000078:	0afffffc 	beq	30000070 <putc+0x8>
    44. 3000007c:	e5c20020 	strb	r0, [r2, #32]
    45. 30000080:	e1a0f00e 	mov	pc, lr
    46.  
    47. 30000084 <puthex>:
    48. 30000084:	e92d4030 	stmdb	sp!, {r4, r5, lr}
    49. 30000088:	e1a05000 	mov	r5, r0
    50. 3000008c:	e3a00030 	mov	r0, #48	; 0x30
    51. 30000090:	ebfffff4 	bl	30000068 <putc>
    52. 30000094:	e3a00078 	mov	r0, #120	; 0x78
    53. 30000098:	e3a04000 	mov	r4, #0	; 0x0
    54. 3000009c:	ebfffff1 	bl	30000068 <putc>
    55. 300000a0:	e2643007 	rsb	r3, r4, #7	; 0x7
    56. 300000a4:	e1a03103 	mov	r3, r3, lsl #2
    57. 300000a8:	e1a03335 	mov	r3, r5, lsr r3
    58. 300000ac:	e203000f 	and	r0, r3, #15	; 0xf
    59. 300000b0:	e3500009 	cmp	r0, #9	; 0x9
    60. 300000b4:	e240300a 	sub	r3, r0, #10	; 0xa
    61. 300000b8:	92800030 	addls	r0, r0, #48	; 0x30
    62. 300000bc:	9a000002 	bls	300000cc <puthex+0x48>
    63. 300000c0:	e3530005 	cmp	r3, #5	; 0x5
    64. 300000c4:	e2803037 	add	r3, r0, #55	; 0x37
    65. 300000c8:	920300ff 	andls	r0, r3, #255	; 0xff
    66. 300000cc:	e2844001 	add	r4, r4, #1	; 0x1
    67. 300000d0:	ebffffe4 	bl	30000068 <putc>
    68. 300000d4:	e3540007 	cmp	r4, #7	; 0x7
    69. 300000d8:	dafffff0 	ble	300000a0 <puthex+0x1c>
    70. 300000dc:	e8bd8030 	ldmia	sp!, {r4, r5, pc}
    71.  
    72. 300000e0 <memsetup>:
    73. 						// sp = 4096
    74. 						
    75. 300000e0:	e92d45f0 	stmdb	sp!, {r4, r5, r6, r7, r8, sl, lr}
    76. 									
    77.  
    78. 300000e4:	e59fc0f4 	ldr	ip, [pc, #244]	; 300001e0 <.text+0x1e0>
    79. 300000e8:	e1a0e00c 	mov	lr, ip  // lr = ip = 30000774
    80. 300000ec:	e8be000f 	ldmia	lr!, {r0, r1, r2, r3}
    81.                         // 去30000774取值，存入r0-r3,本意是把
    82.                         // 22011110 => r0
    83.                         // 0x00000700 => r1
    84.                         // 0x00000700 => r2
    85.                         // 0x00000700 => r3
    86.  
    87.  
    88. 300000f0:	e3a06000 	mov	r6, #0	; 0x0
    89. 300000f4:	e3a08312 	mov	r8, #1207959552	; 0x48000000  // p 
    90. 300000f8:	e3a0a203 	mov	sl, #805306368	; 0x30000000  // mem
    91.  
    92. 300000fc:	e24dd034 	sub	sp, sp, #52	; 0x34
    93.                         // sp=sp-52=4016=0xFB0
    94.  
    95. 30000100:	e1a0c00d 	mov	ip, sp // ip=0xFB0
    96. 30000104:	e8ac000f 	stmia	ip!, {r0, r1, r2, r3}
    97. 						// 把r0-r4这4个值存入栈
    98.  
    99.  
    100. 30000108:	e8be000f 	ldmia	lr!, {r0, r1, r2, r3}
    101. 						// 再从SDRAM里取4个值放入r0-r3
    102. 						// 
    103.  
    104. 3000010c:	e1a0700d 	mov	r7, sp
    105. 30000110:	e8ac000f 	stmia	ip!, {r0, r1, r2, r3}
    106. 						// 把r0-r4这4个值存入栈
    107.  
    108. 30000114:	e8be000f 	ldmia	lr!, {r0, r1, r2, r3}
    109. 30000118:	e59e4000 	ldr	r4, [lr]
    110. 3000011c:	e8ac000f 	stmia	ip!, {r0, r1, r2, r3}
    111. 30000120:	e3a00073 	mov	r0, #115	; 0x73
    112. 30000124:	e58c4000 	str	r4, [ip]
    113. 30000128:	ebffffce 	bl	30000068 <putc>
    114. 3000012c:	e3a00074 	mov	r0, #116	; 0x74
    115. 30000130:	ebffffcc 	bl	30000068 <putc>
    116. 30000134:	e3a00061 	mov	r0, #97	; 0x61
    117. 30000138:	ebffffca 	bl	30000068 <putc>
    118. 3000013c:	e3a00072 	mov	r0, #114	; 0x72
    119. 30000140:	ebffffc8 	bl	30000068 <putc>
    120. 30000144:	e3a00074 	mov	r0, #116	; 0x74
    121. 30000148:	ebffffc6 	bl	30000068 <putc>
    122. 3000014c:	e59f0090 	ldr	r0, [pc, #144]	; 300001e4 <.text+0x1e4>
    123. 30000150:	ebffffcb 	bl	30000084 <puthex>
    124. 30000154:	e28d2034 	add	r2, sp, #52	; 0x34
    125. 30000158:	e1a04106 	mov	r4, r6, lsl #2
    126. 3000015c:	e0843002 	add	r3, r4, r2
    127. 30000160:	e5135034 	ldr	r5, [r3, #-52]
    128. 30000164:	e2860031 	add	r0, r6, #49	; 0x31
    129. 30000168:	e7885106 	str	r5, [r8, r6, lsl #2]
    130. 3000016c:	e20000ff 	and	r0, r0, #255	; 0xff
    131. 30000170:	ebffffbc 	bl	30000068 <putc>
    132. 30000174:	e3a0003a 	mov	r0, #58	; 0x3a
    133. 30000178:	ebffffba 	bl	30000068 <putc>
    134. 3000017c:	e0870004 	add	r0, r7, r4
    135. 30000180:	ebffffbf 	bl	30000084 <puthex>
    136. 30000184:	e3a00020 	mov	r0, #32	; 0x20
    137. 30000188:	ebffffb6 	bl	30000068 <putc>
    138. 3000018c:	e1a00005 	mov	r0, r5
    139. 30000190:	ebffffbb 	bl	30000084 <puthex>
    140. 30000194:	e3a0000a 	mov	r0, #10	; 0xa
    141. 30000198:	ebffffb2 	bl	30000068 <putc>
    142. 3000019c:	e2866001 	add	r6, r6, #1	; 0x1
    143. 300001a0:	e3a0000d 	mov	r0, #13	; 0xd
    144. 300001a4:	ebffffaf 	bl	30000068 <putc>
    145. 300001a8:	e356000c 	cmp	r6, #12	; 0xc
    146. 300001ac:	daffffe8 	ble	30000154 <memsetup+0x74>
    147. 300001b0:	e3a00065 	mov	r0, #101	; 0x65
    148. 300001b4:	ebffffab 	bl	30000068 <putc>
    149. 300001b8:	e3a0006e 	mov	r0, #110	; 0x6e
    150. 300001bc:	ebffffa9 	bl	30000068 <putc>
    151. 300001c0:	e3a00064 	mov	r0, #100	; 0x64
    152. 300001c4:	ebffffa7 	bl	30000068 <putc>
    153. 300001c8:	e3a0304b 	mov	r3, #75	; 0x4b
    154. 300001cc:	e5ca3000 	strb	r3, [sl]
    155. 300001d0:	e5da0000 	ldrb	r0, [sl]
    156. 300001d4:	ebffffa3 	bl	30000068 <putc>
    157. 300001d8:	e28dd034 	add	sp, sp, #52	; 0x34
    158. 300001dc:	e8bd85f0 	ldmia	sp!, {r4, r5, r6, r7, r8, sl, pc}
    159. 300001e0:	30000774 	andcc	r0, r0, r4, ror r7
    160. 300001e4:	1234abcd 	eornes	sl, r4, #209920	; 0x33400
    161.  
    162. 300001e8 <uart0_init>:
    163. 300001e8:	e52de004 	str	lr, [sp, #-4]!
    164. 300001ec:	e3a02456 	mov	r2, #1442840576	; 0x56000000
    165. 300001f0:	e3a0e00c 	mov	lr, #12	; 0xc
    166. 300001f4:	e3a0c205 	mov	ip, #1342177280	; 0x50000000
    167. 300001f8:	e3a01005 	mov	r1, #5	; 0x5
    168. 300001fc:	e3a00000 	mov	r0, #0	; 0x0
    169. 30000200:	e5923070 	ldr	r3, [r2, #112]
    170. 30000204:	e38330a0 	orr	r3, r3, #160	; 0xa0
    171. 30000208:	e5823070 	str	r3, [r2, #112]
    172. 3000020c:	e3a03003 	mov	r3, #3	; 0x3
    173. 30000210:	e582e078 	str	lr, [r2, #120]
    174. 30000214:	e3a02285 	mov	r2, #1342177288	; 0x50000008
    175. 30000218:	e58c3000 	str	r3, [ip]
    176. 3000021c:	e2833215 	add	r3, r3, #1342177281	; 0x50000001
    177. 30000220:	e4831008 	str	r1, [r3], #8
    178. 30000224:	e5820000 	str	r0, [r2]
    179. 30000228:	e5830000 	str	r0, [r3]
    180. 3000022c:	e58ce028 	str	lr, [ip, #40]
    181. 30000230:	e49df004 	ldr	pc, [sp], #4
    182.  
    183. 30000234 <puts>:
    184. 30000234:	e92d4030 	stmdb	sp!, {r4, r5, lr}
    185. 30000238:	e1a05000 	mov	r5, r0
    186. 3000023c:	e3a04000 	mov	r4, #0	; 0x0
    187. 30000240:	e5d00000 	ldrb	r0, [r0]
    188. 30000244:	e3500000 	cmp	r0, #0	; 0x0
    189. 30000248:	08bd8030 	ldmeqia	sp!, {r4, r5, pc}
    190. 3000024c:	e2844001 	add	r4, r4, #1	; 0x1
    191. 30000250:	ebffff84 	bl	30000068 <putc>
    192. 30000254:	e7d50004 	ldrb	r0, [r5, r4]
    193. 30000258:	e3500000 	cmp	r0, #0	; 0x0
    194. 3000025c:	1afffffa 	bne	3000024c <puts+0x18>
    195. 30000260:	e8bd8030 	ldmia	sp!, {r4, r5, pc}
    196.  
    197. 30000264 <s3c2410_nand_select_chip>:
    198. 30000264:	e59f301c 	ldr	r3, [pc, #28]	; 30000288 <.text+0x288>
    199. 30000268:	e5931000 	ldr	r1, [r3]
    200. 3000026c:	e5912000 	ldr	r2, [r1]
    201. 30000270:	e3c22b02 	bic	r2, r2, #2048	; 0x800
    202. 30000274:	e5812000 	str	r2, [r1]
    203. 30000278:	e3a03009 	mov	r3, #9	; 0x9
    204. 3000027c:	e2533001 	subs	r3, r3, #1	; 0x1
    205. 30000280:	5afffffd 	bpl	3000027c <s3c2410_nand_select_chip+0x18>
    206. 30000284:	e1a0f00e 	mov	pc, lr
    207. 30000288:	300006d0 	ldrccd	r0, [r0], -r0
    208.  
    209. 3000028c <s3c2410_write_cmd>:
    210. 3000028c:	e59f3008 	ldr	r3, [pc, #8]	; 3000029c <.text+0x29c>
    211. 30000290:	e5932000 	ldr	r2, [r3]
    212. 30000294:	e5c20004 	strb	r0, [r2, #4]
    213. 30000298:	e1a0f00e 	mov	pc, lr
    214. 3000029c:	300006d0 	ldrccd	r0, [r0], -r0
    215.  
    216. 300002a0 <s3c2410_wait_idle>:
    217. 300002a0:	e59f302c 	ldr	r3, [pc, #44]	; 300002d4 <.text+0x2d4>
    218. 300002a4:	e5931000 	ldr	r1, [r3]
    219. 300002a8:	e5d12010 	ldrb	r2, [r1, #16]
    220. 300002ac:	e3120001 	tst	r2, #1	; 0x1
    221. 300002b0:	e2811010 	add	r1, r1, #16	; 0x10
    222. 300002b4:	11a0f00e 	movne	pc, lr
    223. 300002b8:	e3a03009 	mov	r3, #9	; 0x9
    224. 300002bc:	e2533001 	subs	r3, r3, #1	; 0x1
    225. 300002c0:	5afffffd 	bpl	300002bc <s3c2410_wait_idle+0x1c>
    226. 300002c4:	e5d13000 	ldrb	r3, [r1]
    227. 300002c8:	e3130001 	tst	r3, #1	; 0x1
    228. 300002cc:	0afffff9 	beq	300002b8 <s3c2410_wait_idle+0x18>
    229. 300002d0:	e1a0f00e 	mov	pc, lr
    230. 300002d4:	300006d0 	ldrccd	r0, [r0], -r0
    231.  
    232. 300002d8 <s3c2410_nand_deselect_chip>:
    233. 300002d8:	e59f3010 	ldr	r3, [pc, #16]	; 300002f0 <.text+0x2f0>
    234. 300002dc:	e5931000 	ldr	r1, [r3]
    235. 300002e0:	e5912000 	ldr	r2, [r1]
    236. 300002e4:	e3822b02 	orr	r2, r2, #2048	; 0x800
    237. 300002e8:	e5812000 	str	r2, [r1]
    238. 300002ec:	e1a0f00e 	mov	pc, lr
    239. 300002f0:	300006d0 	ldrccd	r0, [r0], -r0
    240.  
    241. 300002f4 <s3c2410_nand_reset>:
    242. 300002f4:	e52de004 	str	lr, [sp, #-4]!
    243. 300002f8:	ebffffd9 	bl	30000264 <s3c2410_nand_select_chip>
    244. 300002fc:	e3a000ff 	mov	r0, #255	; 0xff
    245. 30000300:	ebffffe1 	bl	3000028c <s3c2410_write_cmd>
    246. 30000304:	ebffffe5 	bl	300002a0 <s3c2410_wait_idle>
    247. 30000308:	e49de004 	ldr	lr, [sp], #4
    248. 3000030c:	eafffff1 	b	300002d8 <s3c2410_nand_deselect_chip>
    249.  
    250. 30000310 <s3c2410_write_addr>:
    251. 30000310:	e59f3054 	ldr	r3, [pc, #84]	; 3000036c <.text+0x36c>
    252. 30000314:	e5932000 	ldr	r2, [r3]
    253. 30000318:	e5c20008 	strb	r0, [r2, #8]
    254. 3000031c:	e3a03009 	mov	r3, #9	; 0x9
    255. 30000320:	e2822008 	add	r2, r2, #8	; 0x8
    256. 30000324:	e2533001 	subs	r3, r3, #1	; 0x1
    257. 30000328:	5afffffd 	bpl	30000324 <s3c2410_write_addr+0x14>
    258. 3000032c:	e1a034a0 	mov	r3, r0, lsr #9
    259. 30000330:	e5c23000 	strb	r3, [r2]
    260. 30000334:	e3a03009 	mov	r3, #9	; 0x9
    261. 30000338:	e2533001 	subs	r3, r3, #1	; 0x1
    262. 3000033c:	5afffffd 	bpl	30000338 <s3c2410_write_addr+0x28>
    263. 30000340:	e1a038a0 	mov	r3, r0, lsr #17
    264. 30000344:	e5c23000 	strb	r3, [r2]
    265. 30000348:	e3a03009 	mov	r3, #9	; 0x9
    266. 3000034c:	e2533001 	subs	r3, r3, #1	; 0x1
    267. 30000350:	5afffffd 	bpl	3000034c <s3c2410_write_addr+0x3c>
    268. 30000354:	e1a03ca0 	mov	r3, r0, lsr #25
    269. 30000358:	e5c23000 	strb	r3, [r2]
    270. 3000035c:	e3a03009 	mov	r3, #9	; 0x9
    271. 30000360:	e2533001 	subs	r3, r3, #1	; 0x1
    272. 30000364:	5afffffd 	bpl	30000360 <s3c2410_write_addr+0x50>
    273. 30000368:	e1a0f00e 	mov	pc, lr
    274. 3000036c:	300006d0 	ldrccd	r0, [r0], -r0
    275.  
    276. 30000370 <s3c2410_read_data>:
    277. 30000370:	e59f3008 	ldr	r3, [pc, #8]	; 30000380 <.text+0x380>
    278. 30000374:	e5932000 	ldr	r2, [r3]
    279. 30000378:	e5d2000c 	ldrb	r0, [r2, #12]
    280. 3000037c:	e1a0f00e 	mov	pc, lr
    281. 30000380:	300006d0 	ldrccd	r0, [r0], -r0
    282.  
    283. 30000384 <s3c2440_nand_select_chip>:
    284. 30000384:	e59f301c 	ldr	r3, [pc, #28]	; 300003a8 <.text+0x3a8>
    285. 30000388:	e5931000 	ldr	r1, [r3]
    286. 3000038c:	e5912004 	ldr	r2, [r1, #4]
    287. 30000390:	e3c22002 	bic	r2, r2, #2	; 0x2
    288. 30000394:	e5812004 	str	r2, [r1, #4]
    289. 30000398:	e3a03009 	mov	r3, #9	; 0x9
    290. 3000039c:	e2533001 	subs	r3, r3, #1	; 0x1
    291. 300003a0:	5afffffd 	bpl	3000039c <s3c2440_nand_select_chip+0x18>
    292. 300003a4:	e1a0f00e 	mov	pc, lr
    293. 300003a8:	300006cc 	andcc	r0, r0, ip, asr #13
    294.  
    295. 300003ac <s3c2440_write_cmd>:
    296. 300003ac:	e59f3008 	ldr	r3, [pc, #8]	; 300003bc <.text+0x3bc>
    297. 300003b0:	e5932000 	ldr	r2, [r3]
    298. 300003b4:	e5c20008 	strb	r0, [r2, #8]
    299. 300003b8:	e1a0f00e 	mov	pc, lr
    300. 300003bc:	300006cc 	andcc	r0, r0, ip, asr #13
    301.  
    302. 300003c0 <s3c2440_wait_idle>:
    303. 300003c0:	e59f302c 	ldr	r3, [pc, #44]	; 300003f4 <.text+0x3f4>
    304. 300003c4:	e5931000 	ldr	r1, [r3]
    305. 300003c8:	e5d12020 	ldrb	r2, [r1, #32]
    306. 300003cc:	e3120001 	tst	r2, #1	; 0x1
    307. 300003d0:	e2811020 	add	r1, r1, #32	; 0x20
    308. 300003d4:	11a0f00e 	movne	pc, lr
    309. 300003d8:	e3a03009 	mov	r3, #9	; 0x9
    310. 300003dc:	e2533001 	subs	r3, r3, #1	; 0x1
    311. 300003e0:	5afffffd 	bpl	300003dc <s3c2440_wait_idle+0x1c>
    312. 300003e4:	e5d13000 	ldrb	r3, [r1]
    313. 300003e8:	e3130001 	tst	r3, #1	; 0x1
    314. 300003ec:	0afffff9 	beq	300003d8 <s3c2440_wait_idle+0x18>
    315. 300003f0:	e1a0f00e 	mov	pc, lr
    316. 300003f4:	300006cc 	andcc	r0, r0, ip, asr #13
    317.  
    318. 300003f8 <s3c2440_nand_deselect_chip>:
    319. 300003f8:	e59f3010 	ldr	r3, [pc, #16]	; 30000410 <.text+0x410>
    320. 300003fc:	e5931000 	ldr	r1, [r3]
    321. 30000400:	e5912004 	ldr	r2, [r1, #4]
    322. 30000404:	e3822002 	orr	r2, r2, #2	; 0x2
    323. 30000408:	e5812004 	str	r2, [r1, #4]
    324. 3000040c:	e1a0f00e 	mov	pc, lr
    325. 30000410:	300006cc 	andcc	r0, r0, ip, asr #13
    326.  
    327. 30000414 <s3c2440_nand_reset>:
    328. 30000414:	e52de004 	str	lr, [sp, #-4]!
    329. 30000418:	ebffffd9 	bl	30000384 <s3c2440_nand_select_chip>
    330. 3000041c:	e3a000ff 	mov	r0, #255	; 0xff
    331. 30000420:	ebffffe1 	bl	300003ac <s3c2440_write_cmd>
    332. 30000424:	ebffffe5 	bl	300003c0 <s3c2440_wait_idle>
    333. 30000428:	e49de004 	ldr	lr, [sp], #4
    334. 3000042c:	eafffff1 	b	300003f8 <s3c2440_nand_deselect_chip>
    335.  
    336. 30000430 <s3c2440_write_addr_lp>:
    337. 30000430:	e59f3078 	ldr	r3, [pc, #120]	; 300004b0 <.text+0x4b0>
    338. 30000434:	e1a01a80 	mov	r1, r0, lsl #21
    339. 30000438:	e5932000 	ldr	r2, [r3]
    340. 3000043c:	e1a01aa1 	mov	r1, r1, lsr #21
    341. 30000440:	e3c13000 	bic	r3, r1, #0	; 0x0
    342. 30000444:	e5c2300c 	strb	r3, [r2, #12]
    343. 30000448:	e1a005a0 	mov	r0, r0, lsr #11
    344. 3000044c:	e282200c 	add	r2, r2, #12	; 0xc
    345. 30000450:	e3a03009 	mov	r3, #9	; 0x9
    346. 30000454:	e2533001 	subs	r3, r3, #1	; 0x1
    347. 30000458:	5afffffd 	bpl	30000454 <s3c2440_write_addr_lp+0x24>
    348. 3000045c:	e1a03421 	mov	r3, r1, lsr #8
    349. 30000460:	e5c23000 	strb	r3, [r2]
    350. 30000464:	e3a03009 	mov	r3, #9	; 0x9
    351. 30000468:	e2533001 	subs	r3, r3, #1	; 0x1
    352. 3000046c:	5afffffd 	bpl	30000468 <s3c2440_write_addr_lp+0x38>
    353. 30000470:	e5c20000 	strb	r0, [r2]
    354. 30000474:	e3a03009 	mov	r3, #9	; 0x9
    355. 30000478:	e2533001 	subs	r3, r3, #1	; 0x1
    356. 3000047c:	5afffffd 	bpl	30000478 <s3c2440_write_addr_lp+0x48>
    357. 30000480:	e1a03440 	mov	r3, r0, asr #8
    358. 30000484:	e5c23000 	strb	r3, [r2]
    359. 30000488:	e3a03009 	mov	r3, #9	; 0x9
    360. 3000048c:	e2533001 	subs	r3, r3, #1	; 0x1
    361. 30000490:	5afffffd 	bpl	3000048c <s3c2440_write_addr_lp+0x5c>
    362. 30000494:	e1a03840 	mov	r3, r0, asr #16
    363. 30000498:	e2033003 	and	r3, r3, #3	; 0x3
    364. 3000049c:	e5c23000 	strb	r3, [r2]
    365. 300004a0:	e3a03009 	mov	r3, #9	; 0x9
    366. 300004a4:	e2533001 	subs	r3, r3, #1	; 0x1
    367. 300004a8:	5afffffd 	bpl	300004a4 <s3c2440_write_addr_lp+0x74>
    368. 300004ac:	e1a0f00e 	mov	pc, lr
    369. 300004b0:	300006cc 	andcc	r0, r0, ip, asr #13
    370.  
    371. 300004b4 <s3c2440_read_data>:
    372. 300004b4:	e59f3008 	ldr	r3, [pc, #8]	; 300004c4 <.text+0x4c4>
    373. 300004b8:	e5932000 	ldr	r2, [r3]
    374. 300004bc:	e5d20010 	ldrb	r0, [r2, #16]
    375. 300004c0:	e1a0f00e 	mov	pc, lr
    376. 300004c4:	300006cc 	andcc	r0, r0, ip, asr #13
    377.  
    378. 300004c8 <write_cmd>:
    379. 300004c8:	e52de004 	str	lr, [sp, #-4]!
    380. 300004cc:	e59f3008 	ldr	r3, [pc, #8]	; 300004dc <.text+0x4dc>
    381. 300004d0:	e1a0e00f 	mov	lr, pc
    382. 300004d4:	e593f010 	ldr	pc, [r3, #16]
    383. 300004d8:	e49df004 	ldr	pc, [sp], #4
    384. 300004dc:	300006d4 	ldrccd	r0, [r0], -r4
    385.  
    386. 300004e0 <nand_init>:
    387. 300004e0:	e52de004 	str	lr, [sp, #-4]!
    388. 300004e4:	e3a0e456 	mov	lr, #1442840576	; 0x56000000
    389. 300004e8:	e3a035c9 	mov	r3, #843055104	; 0x32400000
    390. 300004ec:	e3a015c9 	mov	r1, #843055104	; 0x32400000
    391. 300004f0:	e2833801 	add	r3, r3, #65536	; 0x10000
    392. 300004f4:	e2811801 	add	r1, r1, #65536	; 0x10000
    393. 300004f8:	e3a0cb26 	mov	ip, #38912	; 0x9800
    394. 300004fc:	e2811002 	add	r1, r1, #2	; 0x2
    395. 30000500:	e59f00c8 	ldr	r0, [pc, #200]	; 300005d0 <.text+0x5d0>
    396. 30000504:	e28cc030 	add	ip, ip, #48	; 0x30
    397. 30000508:	e59e20b0 	ldr	r2, [lr, #176]
    398. 3000050c:	e1520003 	cmp	r2, r3
    399. 30000510:	0a00001a 	beq	30000580 <nand_init+0xa0>
    400. 30000514:	e59e30b0 	ldr	r3, [lr, #176]
    401. 30000518:	e1530001 	cmp	r3, r1
    402. 3000051c:	0a000017 	beq	30000580 <nand_init+0xa0>
    403. 30000520:	e59f30ac 	ldr	r3, [pc, #172]	; 300005d4 <.text+0x5d4>
    404. 30000524:	e5931000 	ldr	r1, [r3]
    405. 30000528:	e59f00a0 	ldr	r0, [pc, #160]	; 300005d0 <.text+0x5d0>
    406. 3000052c:	e3a03013 	mov	r3, #19	; 0x13
    407. 30000530:	e59f20a0 	ldr	r2, [pc, #160]	; 300005d8 <.text+0x5d8>
    408. 30000534:	e5813004 	str	r3, [r1, #4]
    409. 30000538:	e59f309c 	ldr	r3, [pc, #156]	; 300005dc <.text+0x5dc>
    410. 3000053c:	e5802000 	str	r2, [r0]
    411. 30000540:	e59f2098 	ldr	r2, [pc, #152]	; 300005e0 <.text+0x5e0>
    412. 30000544:	e5803004 	str	r3, [r0, #4]
    413. 30000548:	e59f3094 	ldr	r3, [pc, #148]	; 300005e4 <.text+0x5e4>
    414. 3000054c:	e5802008 	str	r2, [r0, #8]
    415. 30000550:	e59f2090 	ldr	r2, [pc, #144]	; 300005e8 <.text+0x5e8>
    416. 30000554:	e580300c 	str	r3, [r0, #12]
    417. 30000558:	e59f308c 	ldr	r3, [pc, #140]	; 300005ec <.text+0x5ec>
    418. 3000055c:	e5802010 	str	r2, [r0, #16]
    419. 30000560:	e59f2088 	ldr	r2, [pc, #136]	; 300005f0 <.text+0x5f0>
    420. 30000564:	e5803014 	str	r3, [r0, #20]
    421. 30000568:	e3a03c03 	mov	r3, #768	; 0x300
    422. 3000056c:	e5802018 	str	r2, [r0, #24]
    423. 30000570:	e5813000 	str	r3, [r1]
    424. 30000574:	e1a0e00f 	mov	lr, pc
    425. 30000578:	e590f000 	ldr	pc, [r0]
    426. 3000057c:	e49df004 	ldr	pc, [sp], #4
    427. 30000580:	e59f306c 	ldr	r3, [pc, #108]	; 300005f4 <.text+0x5f4>
    428. 30000584:	e5932000 	ldr	r2, [r3]
    429. 30000588:	e59f3068 	ldr	r3, [pc, #104]	; 300005f8 <.text+0x5f8>
    430. 3000058c:	e582c000 	str	ip, [r2]
    431. 30000590:	e59f2064 	ldr	r2, [pc, #100]	; 300005fc <.text+0x5fc>
    432. 30000594:	e5803000 	str	r3, [r0]
    433. 30000598:	e59f3060 	ldr	r3, [pc, #96]	; 30000600 <.text+0x600>
    434. 3000059c:	e5802004 	str	r2, [r0, #4]
    435. 300005a0:	e59f205c 	ldr	r2, [pc, #92]	; 30000604 <.text+0x604>
    436. 300005a4:	e5803008 	str	r3, [r0, #8]
    437. 300005a8:	e59f3058 	ldr	r3, [pc, #88]	; 30000608 <.text+0x608>
    438. 300005ac:	e580200c 	str	r2, [r0, #12]
    439. 300005b0:	e59f2054 	ldr	r2, [pc, #84]	; 3000060c <.text+0x60c>
    440. 300005b4:	e5803010 	str	r3, [r0, #16]
    441. 300005b8:	e59f3050 	ldr	r3, [pc, #80]	; 30000610 <.text+0x610>
    442. 300005bc:	e5802014 	str	r2, [r0, #20]
    443. 300005c0:	e5803018 	str	r3, [r0, #24]
    444. 300005c4:	e1a0e00f 	mov	lr, pc
    445. 300005c8:	e590f000 	ldr	pc, [r0]
    446. 300005cc:	e49df004 	ldr	pc, [sp], #4
    447. 300005d0:	300006d4 	ldrccd	r0, [r0], -r4
    448. 300005d4:	300006cc 	andcc	r0, r0, ip, asr #13
    449. 300005d8:	30000414 	andcc	r0, r0, r4, lsl r4
    450. 300005dc:	300003c0 	andcc	r0, r0, r0, asr #7
    451. 300005e0:	30000384 	andcc	r0, r0, r4, lsl #7
    452. 300005e4:	300003f8 	strccd	r0, [r0], -r8
    453. 300005e8:	300003ac 	andcc	r0, r0, ip, lsr #7
    454. 300005ec:	30000430 	andcc	r0, r0, r0, lsr r4
    455. 300005f0:	300004b4 	strcch	r0, [r0], -r4
    456. 300005f4:	300006d0 	ldrccd	r0, [r0], -r0
    457. 300005f8:	300002f4 	strccd	r0, [r0], -r4
    458. 300005fc:	300002a0 	andcc	r0, r0, r0, lsr #5
    459. 30000600:	30000264 	andcc	r0, r0, r4, ror #4
    460. 30000604:	300002d8 	ldrccd	r0, [r0], -r8
    461. 30000608:	3000028c 	andcc	r0, r0, ip, lsl #5
    462. 3000060c:	30000310 	andcc	r0, r0, r0, lsl r3
    463. 30000610:	30000370 	andcc	r0, r0, r0, ror r3
    464.  
    465. 30000614 <nand_read>:
    466. 30000614:	e1a03a81 	mov	r3, r1, lsl #21
    467. 30000618:	e1a03aa3 	mov	r3, r3, lsr #21
    468. 3000061c:	e3530000 	cmp	r3, #0	; 0x0
    469. 30000620:	e92d45f0 	stmdb	sp!, {r4, r5, r6, r7, r8, sl, lr}
    470. 30000624:	e1a05001 	mov	r5, r1
    471. 30000628:	e1a06000 	mov	r6, r0
    472. 3000062c:	e1a04002 	mov	r4, r2
    473. 30000630:	18bd85f0 	ldmneia	sp!, {r4, r5, r6, r7, r8, sl, pc}
    474. 30000634:	e1a03a82 	mov	r3, r2, lsl #21
    475. 30000638:	e1a03aa3 	mov	r3, r3, lsr #21
    476. 3000063c:	e3530000 	cmp	r3, #0	; 0x0
    477. 30000640:	18bd85f0 	ldmneia	sp!, {r4, r5, r6, r7, r8, sl, pc}
    478. 30000644:	e59f807c 	ldr	r8, [pc, #124]	; 300006c8 <.text+0x6c8>
    479. 30000648:	e1a0e00f 	mov	lr, pc
    480. 3000064c:	e598f008 	ldr	pc, [r8, #8]
    481. 30000650:	e3a03009 	mov	r3, #9	; 0x9
    482. 30000654:	e2533001 	subs	r3, r3, #1	; 0x1
    483. 30000658:	5afffffd 	bpl	30000654 <nand_read+0x40>
    484. 3000065c:	e085a004 	add	sl, r5, r4
    485. 30000660:	e155000a 	cmp	r5, sl
    486. 30000664:	2a000014 	bcs	300006bc <nand_read+0xa8>
    487. 30000668:	e3a07e7f 	mov	r7, #2032	; 0x7f0
    488. 3000066c:	e287700f 	add	r7, r7, #15	; 0xf
    489. 30000670:	e3a00000 	mov	r0, #0	; 0x0
    490. 30000674:	ebffff93 	bl	300004c8 <write_cmd>
    491. 30000678:	e1a00005 	mov	r0, r5
    492. 3000067c:	e1a0e00f 	mov	lr, pc
    493. 30000680:	e598f014 	ldr	pc, [r8, #20]
    494. 30000684:	e3a00030 	mov	r0, #48	; 0x30
    495. 30000688:	ebffff8e 	bl	300004c8 <write_cmd>
    496. 3000068c:	e1a0e00f 	mov	lr, pc
    497. 30000690:	e598f004 	ldr	pc, [r8, #4]
    498. 30000694:	e3a04000 	mov	r4, #0	; 0x0
    499. 30000698:	e1a0e00f 	mov	lr, pc
    500. 3000069c:	e598f018 	ldr	pc, [r8, #24]
    501. 300006a0:	e2844001 	add	r4, r4, #1	; 0x1
    502. 300006a4:	e1540007 	cmp	r4, r7
    503. 300006a8:	e4c60001 	strb	r0, [r6], #1
    504. 300006ac:	e2855001 	add	r5, r5, #1	; 0x1
    505. 300006b0:	dafffff8 	ble	30000698 <nand_read+0x84>
    506. 300006b4:	e155000a 	cmp	r5, sl
    507. 300006b8:	3affffec 	bcc	30000670 <nand_read+0x5c>
    508. 300006bc:	e1a0e00f 	mov	lr, pc
    509. 300006c0:	e598f00c 	ldr	pc, [r8, #12]
    510. 300006c4:	e8bd85f0 	ldmia	sp!, {r4, r5, r6, r7, r8, sl, pc}
    511. 300006c8:	300006d4 	ldrccd	r0, [r0], -r4
    512.  
    513. 300006cc <s3c2440nand>:
    514. 300006cc:	4e000000 	cdpmi	0, 0, cr0, cr0, cr0, {0}
    515.  
    516. 300006d0 <s3c2410nand>:
    517. 300006d0:	4e000000 	cdpmi	0, 0, cr0, cr0, cr0, {0}
    518.  
    519. 300006d4 <nand_chip>:
    520. 	...
    521. 300006f0:	43434700 	cmpmi	r3, #0	; 0x0
    522. 300006f4:	4728203a 	undefined
    523. 300006f8:	2029554e 	eorcs	r5, r9, lr, asr #10
    524. 300006fc:	2e342e33 	mrccs	14, 1, r2, cr4, cr3, {1}
    525. 30000700:	00000035 	andeq	r0, r0, r5, lsr r0
    526.  
    527. 30000704 <wait>:
    528. 30000704:	e24dd004 	sub	sp, sp, #4	; 0x4
    529. 30000708:	e58d0000 	str	r0, [sp]
    530. 3000070c:	e59d3000 	ldr	r3, [sp]
    531. 30000710:	e3530000 	cmp	r3, #0	; 0x0
    532. 30000714:	0a000005 	beq	30000730 <wait+0x2c>
    533. 30000718:	e59d3000 	ldr	r3, [sp]
    534. 3000071c:	e2433001 	sub	r3, r3, #1	; 0x1
    535. 30000720:	e58d3000 	str	r3, [sp]
    536. 30000724:	e59d2000 	ldr	r2, [sp]
    537. 30000728:	e3520000 	cmp	r2, #0	; 0x0
    538. 3000072c:	1afffff9 	bne	30000718 <wait+0x14>
    539. 30000730:	e28dd004 	add	sp, sp, #4	; 0x4
    540. 30000734:	e1a0f00e 	mov	pc, lr
    541.  
    542. 30000738 <main>:
    543. 30000738:	e3a02456 	mov	r2, #1442840576	; 0x56000000
    544. 3000073c:	e3a03c15 	mov	r3, #5376	; 0x1500
    545. 30000740:	e92d4030 	stmdb	sp!, {r4, r5, lr}
    546. 30000744:	e1a05002 	mov	r5, r2
    547. 30000748:	e3a04000 	mov	r4, #0	; 0x0
    548. 3000074c:	e5823050 	str	r3, [r2, #80]
    549. 30000750:	e3a00c75 	mov	r0, #29952	; 0x7500
    550. 30000754:	e2800030 	add	r0, r0, #48	; 0x30
    551. 30000758:	ebffffe9 	bl	30000704 <wait>
    552. 3000075c:	e1e03204 	mvn	r3, r4, lsl #4
    553. 30000760:	e2844001 	add	r4, r4, #1	; 0x1
    554. 30000764:	e3540008 	cmp	r4, #8	; 0x8
    555. 30000768:	02444008 	subeq	r4, r4, #8	; 0x8
    556. 3000076c:	e5853054 	str	r3, [r5, #84]
    557. 30000770:	eafffff6 	b	30000750 <main+0x18>
    558. Disassembly of section .rodata:
    559.  
    560. 30000774 <.rodata>:
    561. 30000774:	22011110 	andcs	r1, r1, #4	; 0x4
    562. 30000778:	00000700 	andeq	r0, r0, r0, lsl #14
    563. 3000077c:	00000700 	andeq	r0, r0, r0, lsl #14
    564. 30000780:	00000700 	andeq	r0, r0, r0, lsl #14
    565. 30000784:	00000700 	andeq	r0, r0, r0, lsl #14
    566. 30000788:	00000700 	andeq	r0, r0, r0, lsl #14
    567. 3000078c:	00000700 	andeq	r0, r0, r0, lsl #14
    568. 30000790:	00018005 	andeq	r8, r1, r5
    569. 30000794:	00018005 	andeq	r8, r1, r5
    570. 30000798:	008c07a3 	addeq	r0, ip, r3, lsr #15
    571. 3000079c:	000000b1 	streqh	r0, [r0], -r1
    572. 300007a0:	00000030 	andeq	r0, r0, r0, lsr r0
    573. 300007a4:	00000030 	andeq	r0, r0, r0, lsr r0
    574. Disassembly of section .comment:
    575.  
    576. 00000000 <.comment>:
    577.    0:	43434700 	cmpmi	r3, #0	; 0x0
    578.    4:	4728203a 	undefined
    579.    8:	2029554e 	eorcs	r5, r9, lr, asr #10
    580.    c:	2e342e33 	mrccs	14, 1, r2, cr4, cr3, {1}
    581.   10:	47000035 	smladxmi	r0, r5, r0, r0
    582.   14:	203a4343 	eorcss	r4, sl, r3, asr #6
    583.   18:	554e4728 	strplb	r4, [lr, #-1832]
    584.   1c:	2e332029 	cdpcs	0, 3, cr2, cr3, cr9, {1}
    585.   20:	00352e34 	eoreqs	r2, r5, r4, lsr lr

     下面算一下为什么是FB0，

     那么反汇编里面，

     所以堆栈4096首先存了7个值，那么4096-7*4，然后又减去52，最后值就是4016=FB0了，然后这里就是保存我们的mem_cfg_val数组，这些值本来应该是。

     但是由于这些值是从0x30000774这里取出来的，但是现在SDRAM(SDRAM从0x30000000开始的)都还没初始化，那这个位置的值肯定是乱码是随机数，

     再总结一遍就是

     这个mem_cfg_val这个变量是在栈里面的，而初始值0x22011110这些值是存在程序里面的，我们去读这些值赋给栈的时候，用的是这些值的链接地址，链接地址是在SDRAM里面，SDRAM还没初始化呢，所以说这些值是乱码。 

  • 相关阅读:
    面试题-谈谈你对JVM的理解
    Maven常用命令与测试和打包项目
    外贸客户来源的渠道有哪些?
    计算机图形学--笔记3
    Nanoprobes 棕榈酰纳米金相关说明书
    Python基础教程（二十四）：日期和时间
    git命令汇总
    【Git实战】协同开发，如何紧急修复线上bug？
    记录解决uniapp使用uview-plus在vue3+vite+ts项目中打包后样式不能显示问题
    微信、支付宝、百度、抖音开放平台第三方代小程序开发总结
  • 原文地址：https://blog.csdn.net/u013171226/article/details/125426326