Chinaunix首页 | 论坛 | 博客

wangcong02345wangcong02345.blog.chinaunix.net

首页　| 　博文目录　| 　关于我

wangcong02345

  • 博客访问： 2148984
  • 博文数量： 438
  • 博客积分： 3871
  • 博客等级： 中校
  • 技术积分： 6075
  • 用 户 组： 普通用户
  • 注册时间： 2011-09-10 00:11
个人简介

邮箱: wangcong02345@163.com

文章分类

全部博文（438）

文章存档

2017年（15）

2016年（119）

2015年（91）

2014年（62）

2013年（56）

2012年（79）

2011年（16）

我的朋友
最近访客
推荐博文
相关博文
TQ2440裸板学习笔记8--实现printf

分类： LINUX

2012-05-30 11:03:41

一、 
   现在串口只能打印字符串，没有实现格式化输出的功能，所以变量的值还不能打印出来。"逐行打印技术"没法实施，这太痛苦了，马上加入printf。
二、代码
root@ubuntu:~/myboot# tree
.
├── main.c
├── Makefile
├── nand.c
├── nand.h
├── sdram.c
├── start.S
├── uart.c
├── uart.h
├── u-boot.lds
└── vsprintf.c
0 directories, 10 files
2.1 uart.c 加入uart_printf的实现

点击(此处)折叠或打开

  1. #include
  2. #define GPHCON (* (volatile unsigned int *) 0x56000070)
  3. #define GPHUP (* (volatile unsigned int *) 0x56000078)

  4.
  5. #define ULCON0 (* (volatile unsigned int *) 0x50000000)
  6. #define UCON0 (* (volatile unsigned int *) 0x50000004)
  7. #define UFCON0 (* (volatile unsigned int *) 0x50000008)
  8. #define UMCON0 (* (volatile unsigned int *) 0x5000000C)
  9. #define UTRSTAT0 (* (volatile unsigned int *) 0x50000010)
  10. #define UERSTAT0 (* (volatile unsigned int *) 0x50000014)
  11. #define UFSTAT0 (* (volatile unsigned int *) 0x50000018)
  12. #define UMSTAT0 (* (volatile unsigned int *) 0x5000001C)
  13. #define UTXH0 (* (volatile unsigned char *) 0x50000020) //类型为:char*
  14. #define URXH0 (* (volatile unsigned char *) 0x50000024)
  15. #define UBRDIV0 (* (volatile unsigned int *) 0x50000028)

  17. #define BAUD_RATE 115200

  18.
  19. void uart_init(void)
  20. {
  21.     GPHCON = 0x000000A0;
  22.     GPHUP = 0x000007FF;
  23.     ULCON0 = (0x03); //8N1        
  24.     UCON0 = (0x01<<2)|(0x01);
  25.     UFCON0 = 0;
  26.     UMCON0 = 0;
  27.     UBRDIV0 = (int)((50*1000*1000)/(BAUD_RATE*16))-1;
  28. }

  29.
  1. unsigned char uart_getc(void)
  2. {
  3.     while(!(UTRSTAT0 & 0x01))
  4.         ;
  5.     return (URXH0 & 0xff);
  6. }

  7.
  8. void uart_putc(char c)
  9. {
  10.     while (!(UTRSTAT0&0x02))
  11.         ;
  12.     UTXH0 = c;
  13.     if('\n' == c)
  14.         uart_putc('\r');
  15. }

  16.
  17. void uart_puts(char *s)
  18. {
  19.     while (*s)
  20.     {
  21.         uart_putc(*s++);
  22.     }
  23. }
  24. /*uart_printf*/
  25. void uart_printf(char *fmt, ...)
  26. {
  27.     va_list ap;
  28.     char buf[256];
  29.     va_start(ap, fmt);
  30.     vsprintf(buf, fmt, ap);
  31.     uart_puts(buf);
  32.     va_end(ap);
  33. }
2.2 vsprintf.c 从linux_0.11 copy过来，稍做修改

点击(此处)折叠或打开

  1. #include <stdarg.h>
  2. /* we use this so that we can do without the ctype library */
  3. #define is_digit(c)    ((c) >= '0' && (c) <= '9')
  4. int strlen(const char *s)
  5. {
  6.     const char *sc;
  7.     for(sc=s; *sc!='\0'; ++sc)
  8.         ;
  9.     return (sc-s);
  10. }

  12. static int skip_atoi(const char **s)
  13. {
  14.     int i=0;

  16.     while (is_digit(**s))
  17.         i = i*10 + *((*s)++) - '0';
  18.     return i;
  19. }

  21. #define ZEROPAD    1        /* pad with zero */
  22. #define SIGN    2        /* unsigned/signed long */
  23. #define PLUS    4        /* show plus */
  24. #define SPACE    8        /* space if plus */
  25. #define LEFT    16        /* left justified */
  26. #define SPECIAL    32        /* 0x */
  27. #define SMALL    64        /* use 'abcdef' instead of 'ABCDEF' */

  29. #if 0
  30. #define do_div(n,base) ({ \
  31. int __res; \
  32. __asm__("divl %4":"=a" (n),"=d" (__res):"0" (n),"1" (0),"r" (base)); \
  33. __res; })
  34. #endif

  36. #define do_div(n,base) ({ \
  37.     int __res; \
  38.     __res = ((unsigned long) n) % (unsigned) base; \
  39.     n = ((unsigned long) n) / (unsigned) base; \
  40.     __res; \
  41. })

  43. static char * number(char * str, int num, int base, int size, int precision
  44.     ,int type)
  45. {
  46.     char c,sign,tmp[36];
  47.     const char *digits="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  48.     int i;

  50.     if (type&SMALL) digits="0123456789abcdefghijklmnopqrstuvwxyz";
  51.     if (type&LEFT) type &= ~ZEROPAD;
  52.     if (base<2 || base>36)
  53.         return 0;
  54.     c = (type & ZEROPAD) ? '0' : ' ' ;
  55.     if (type&SIGN && num<0) {
  56.         sign='-';
  57.         num = -num;
  58.     } else
  59.         sign=(type&PLUS) ? '+' : ((type&SPACE) ? ' ' : 0);
  60.     if (sign) size--;
  61.     if (type&SPECIAL) {
  62.         if (base==16) size -= 2;
  63.         else if (base==8) size--;
  64.     }
  65.     i=0;
  66.     if (num==0)
  67.         tmp[i++]='0';
  68.     else while (num!=0)
  69.         tmp[i++]=digits[do_div(num,base)];
  70.     if (i>precision) precision=i;
  71.     size -= precision;
  72.     if (!(type&(ZEROPAD+LEFT)))
  73.         while(size-->0)
  74.             *str++ = ' ';
  75.     if (sign)
  76.         *str++ = sign;
  77.     if (type&SPECIAL) {
  78.         if (base==8)
  79.             *str++ = '0';
  80.         else if (base==16) {
  81.             *str++ = '0';
  82.             *str++ = digits[33];
  83.         }
  84.     }
  85.     if (!(type&LEFT))
  86.         while(size-->0)
  87.             *str++ = c;
  88.     while(i<precision--)
  89.         *str++ = '0';
  90.     while(i-->0)
  91.         *str++ = tmp[i];
  92.     while(size-->0)
  93.         *str++ = ' ';
  94.     return str;
  95. }

  97. int vsprintf(char *buf, const char *fmt, va_list args)
  98. {
  99.     int len;
  100.     int i;
  101.     char * str;
  102.     char *s;
  103.     int *ip;

  105.     int flags;        /* flags to number() */

  107.     int field_width;    /* width of output field */
  108.     int precision;        /* min. # of digits for integers; max
  109.                  number of chars for from string */
  110.     int qualifier;        /* 'h', 'l', or 'L' for integer fields */

  112.     for (str=buf ; *fmt ; ++fmt) {
  113.         if (*fmt != '%') {
  114.             *str++ = *fmt;
  115.             continue;
  116.         }
  117.             
  118.         /* process flags */
  119.         flags = 0;
  120.         repeat:
  121.             ++fmt;        /* this also skips first '%' */
  122.             switch (*fmt) {
  123.                 case '-': flags |= LEFT; goto repeat;
  124.                 case '+': flags |= PLUS; goto repeat;
  125.                 case ' ': flags |= SPACE; goto repeat;
  126.                 case '#': flags |= SPECIAL; goto repeat;
  127.                 case '0': flags |= ZEROPAD; goto repeat;
  128.                 }
  129.         
  130.         /* get field width */
  131.         field_width = -1;
  132.         if (is_digit(*fmt))
  133.             field_width = skip_atoi(&fmt);
  134.         else if (*fmt == '*') {
  135.             /* it's the next argument */
  136.             field_width = va_arg(args, int);
  137.             if (field_width < 0) {
  138.                 field_width = -field_width;
  139.                 flags |= LEFT;
  140.             }
  141.         }

  143.         /* get the precision */
  144.         precision = -1;
  145.         if (*fmt == '.') {
  146.             ++fmt;    
  147.             if (is_digit(*fmt))
  148.                 precision = skip_atoi(&fmt);
  149.             else if (*fmt == '*') {
  150.                 /* it's the next argument */
  151.                 precision = va_arg(args, int);
  152.             }
  153.             if (precision < 0)
  154.                 precision = 0;
  155.         }

  157.         /* get the conversion qualifier */
  158.         qualifier = -1;
  159.         if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L') {
  160.             qualifier = *fmt;
  161.             ++fmt;
  162.         }

  164.         switch (*fmt) {
  165.         case 'c':
  166.             if (!(flags & LEFT))
  167.                 while (--field_width > 0)
  168.                     *str++ = ' ';
  169.             *str++ = (unsigned char) va_arg(args, int);
  170.             while (--field_width > 0)
  171.                 *str++ = ' ';
  172.             break;

  174.         case 's':
  175.             s = va_arg(args, char *);
  176.             len = strlen(s);
  177.             if (precision < 0)
  178.                 precision = len;
  179.             else if (len > precision)
  180.                 len = precision;

  182.             if (!(flags & LEFT))
  183.                 while (len < field_width--)
  184.                     *str++ = ' ';
  185.             for (i = 0; i < len; ++i)
  186.                 *str++ = *s++;
  187.             while (len < field_width--)
  188.                 *str++ = ' ';
  189.             break;

  191.         case 'o':
  192.             str = number(str, va_arg(args, unsigned long), 8,
  193.                 field_width, precision, flags);
  194.             break;

  196.         case 'p':
  197.             if (field_width == -1) {
  198.                 field_width = 8;
  199.                 flags |= ZEROPAD;
  200.             }
  201.             str = number(str,
  202.                 (unsigned long) va_arg(args, void *), 16,
  203.                 field_width, precision, flags);
  204.             break;

  206.         case 'x':
  207.             flags |= SMALL;
  208.         case 'X':
  209.             str = number(str, va_arg(args, unsigned long), 16,
  210.                 field_width, precision, flags);
  211.             break;

  213.         case 'd':
  214.         case 'i':
  215.             flags |= SIGN;
  216.         case 'u':
  217.             str = number(str, va_arg(args, unsigned long), 10,
  218.                 field_width, precision, flags);
  219.             break;

  221.         case 'n':
  222.             ip = va_arg(args, int *);
  223.             *ip = (str - buf);
  224.             break;

  226.         default:
  227.             if (*fmt != '%')
  228.                 *str++ = '%';
  229.             if (*fmt)
  230.                 *str++ = *fmt;
  231.             else
  232.                 --fmt;
  233.             break;
  234.         }
  235.     }
  236.     *str = '\0';
  237.     return str-buf;
  238. }
2.3 main.c 测试一下

点击(此处)折叠或打开

  1. #include "uart.h"

  3. void main(void)
  4. {
  5.     char c;
  6.     uart_init();        //初始化串口

  8.     while(1)
  9.     {
  10.         c = uart_getc();
  11.         uart_printf("input char=%c\n",c);
  12.         uart_printf("input char=%d\n",c);
  13.         uart_printf("input char=%x\n",c);
  14.     }
  15. }
2.4 Makefile 需要修改连接部分

点击(此处)折叠或打开

  1. u-boot: $(OBJS) $(LDSCRIPT)
  2. $(LD) $(LDFLAGS) $(OBJS) $(PLATFORM_LIBS) -Map u-boot.map -o u-boot
   2.4.1 将$(PLATFORM_LIBS)变量加入，连接时需要libgcc.a库，否则会提示
vsprintf.o(.text+0x2e4): In function `number':
: undefined reference to `__umodsi3'
vsprintf.o(.text+0x300): In function `number':
: undefined reference to `__udivsi3'
make: *** [u-boot] Error 1
  2.4.2 注意连接顺序，$(PLATFORM_LIBS)一定要放在$(OBJS)后面才行。

 myboot_printf.rar   (使用时，将后缀名rar改为tar.gz)



阅读(2446) | 评论(0) | 转发(1) |
0

上一篇：TQ2440裸板学习笔记7--串口

下一篇：TQ2440裸板学习笔记9--引导内核

给主人留下些什么吧！~~
关于我们 | 关于IT168 | 联系方式 | 广告合作 | 法律声明 | 免费注册

Copyright 2001-2010 ChinaUnix.net All Rights Reserved 北京皓辰网域网络信息技术有限公司. 版权所有

感谢所有关心和支持过ChinaUnix的朋友们

16024965号-6