🆕 malloc 、printf

user/libs/libc/printf.c

@@ -0,0 +1,536 @@
+#include "printf.h"
+
+#include <libc/stdio.h>
+#include <libsystem/syscall.h>
+#include <libc/string.h>
+#include <libc/math.h>
+#include <libc/stdlib.h>
+
+static char *write_num(char *str, uint64_t num, int base, int field_width, int precision, int flags);
+static char *write_float_point_num(char *str, double num, int field_width, int precision, int flags);
+
+/**
+ * @brief 往屏幕上输出字符串
+ *
+ * @param str 字符串指针
+ * @param front_color 前景色
+ * @param bg_color 背景色
+ * @return int64_t
+ */
+int64_t put_string(char *str, uint64_t front_color, uint64_t bg_color)
+{
+    return syscall_invoke(SYS_PUT_STRING, (uint64_t)str, front_color, bg_color, 0, 0, 0, 0, 0);
+}
+
+int printf(const char *fmt, ...)
+{
+    char buf[4096];
+    int count = 0;
+    va_list args;
+    va_start(args, fmt);
+
+    count = vsprintf(buf, fmt, args);
+    va_end(args);
+    put_string(buf, COLOR_WHITE, COLOR_BLACK);
+    return count;
+}
+
+int sprintf(char *buf, const char *fmt, ...)
+{
+    int count = 0;
+    va_list args;
+
+    va_start(args, fmt);
+    count = vsprintf(buf, fmt, args);
+    va_end(args);
+
+    return count;
+}
+
+int vsprintf(char *buf, const char *fmt, va_list args)
+{
+    /**
+     * 将字符串按照fmt和args中的内容进行格式化，然后保存到buf中
+     * @param buf 结果缓冲区
+     * @param fmt 格式化字符串
+     * @param args 内容
+     * @return 最终字符串的长度
+     */
+
+    char *str, *s;
+
+    str = buf;
+
+    int flags;       // 用来存储格式信息的bitmap
+    int field_width; //区域宽度
+    int precision;   //精度
+    int qualifier;   //数据显示的类型
+    int len;
+
+    //开始解析字符串
+    for (; *fmt; ++fmt)
+    {
+        //内容不涉及到格式化，直接输出
+        if (*fmt != '%')
+        {
+            *str = *fmt;
+            ++str;
+            continue;
+        }
+
+        //开始格式化字符串
+
+        //清空标志位和field宽度
+        field_width = flags = 0;
+
+        bool flag_tmp = true;
+        bool flag_break = false;
+
+        ++fmt;
+        while (flag_tmp)
+        {
+            switch (*fmt)
+            {
+            case '\0':
+                //结束解析
+                flag_break = true;
+                flag_tmp = false;
+                break;
+
+            case '-':
+                // 左对齐
+                flags |= LEFT;
+                ++fmt;
+                break;
+            case '+':
+                //在正数前面显示加号
+                flags |= PLUS;
+                ++fmt;
+                break;
+            case ' ':
+                flags |= SPACE;
+                ++fmt;
+                break;
+            case '#':
+                //在八进制数前面显示 '0o'，在十六进制数前面显示 '0x' 或 '0X'
+                flags |= SPECIAL;
+                ++fmt;
+                break;
+            case '0':
+                //显示的数字之前填充‘0’来取代空格
+                flags |= PAD_ZERO;
+                ++fmt;
+                break;
+            default:
+                flag_tmp = false;
+                break;
+            }
+        }
+        if (flag_break)
+            break;
+
+        //获取区域宽度
+        field_width = -1;
+        if (*fmt == '*')
+        {
+            field_width = va_arg(args, int);
+            ++fmt;
+        }
+        else if (is_digit(*fmt))
+        {
+            field_width = atoi(&fmt);
+            if (field_width < 0)
+            {
+                field_width = -field_width;
+                flags |= LEFT;
+            }
+        }
+
+        //获取小数精度
+        precision = -1;
+        if (*fmt == '.')
+        {
+            ++fmt;
+            if (*fmt == '*')
+            {
+                precision = va_arg(args, int);
+                ++fmt;
+            }
+            else if is_digit (*fmt)
+            {
+                precision = atoi(&fmt);
+            }
+        }
+
+        //获取要显示的数据的类型
+        if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L' || *fmt == 'Z')
+        {
+            qualifier = *fmt;
+            ++fmt;
+        }
+        //为了支持lld
+        if (qualifier == 'l' && *fmt == 'l', *(fmt + 1) == 'd')
+            ++fmt;
+
+        //转化成字符串
+        long long *ip;
+        switch (*fmt)
+        {
+        //输出 %
+        case '%':
+            *str++ = '%';
+
+            break;
+        // 显示一个字符
+        case 'c':
+            //靠右对齐
+            if (!(flags & LEFT))
+            {
+                while (--field_width > 0)
+                {
+                    *str = ' ';
+                    ++str;
+                }
+            }
+
+            *str++ = (unsigned char)va_arg(args, int);
+
+            while (--field_width > 0)
+            {
+                *str = ' ';
+                ++str;
+            }
+
+            break;
+
+        //显示一个字符串
+        case 's':
+            s = va_arg(args, char *);
+            if (!s)
+                s = '\0';
+            len = strlen(s);
+            if (precision < 0)
+            {
+                //未指定精度
+                precision = len;
+            }
+
+            else if (len > precision)
+            {
+                len = precision;
+            }
+
+            //靠右对齐
+            if (!(flags & LEFT))
+                while (len < field_width--)
+                {
+                    *str = ' ';
+                    ++str;
+                }
+
+            for (int i = 0; i < len; i++)
+            {
+                *str = *s;
+                ++s;
+                ++str;
+            }
+
+            while (len < field_width--)
+            {
+                *str = ' ';
+                ++str;
+            }
+
+            break;
+        //以八进制显示字符串
+        case 'o':
+            flags |= SMALL;
+        case 'O':
+            flags |= SPECIAL;
+            if (qualifier == 'l')
+                str = write_num(str, va_arg(args, long long), 8, field_width, precision, flags);
+            else
+                str = write_num(str, va_arg(args, int), 8, field_width, precision, flags);
+            break;
+
+        //打印指针指向的地址
+        case 'p':
+            if (field_width == 0)
+            {
+                field_width = 2 * sizeof(void *);
+                flags |= PAD_ZERO;
+            }
+
+            str = write_num(str, (unsigned long)va_arg(args, void *), 16, field_width, precision, flags);
+
+            break;
+
+        //打印十六进制
+        case 'x':
+            flags |= SMALL;
+        case 'X':
+            // flags |= SPECIAL;
+            if (qualifier == 'l')
+                str = write_num(str, va_arg(args, int64_t), 16, field_width, precision, flags);
+            else
+                str = write_num(str, va_arg(args, int), 16, field_width, precision, flags);
+            break;
+
+        //打印十进制有符号整数
+        case 'i':
+        case 'd':
+
+            flags |= SIGN;
+            if (qualifier == 'l')
+                str = write_num(str, va_arg(args, long long), 10, field_width, precision, flags);
+            else
+                str = write_num(str, va_arg(args, int), 10, field_width, precision, flags);
+            break;
+
+        //打印十进制无符号整数
+        case 'u':
+            if (qualifier == 'l')
+                str = write_num(str, va_arg(args, unsigned long long), 10, field_width, precision, flags);
+            else
+                str = write_num(str, va_arg(args, unsigned int), 10, field_width, precision, flags);
+            break;
+
+        //输出有效字符数量到*ip对应的变量
+        case 'n':
+
+            if (qualifier == 'l')
+                ip = va_arg(args, long long *);
+            else
+                ip = (int64_t *)va_arg(args, int *);
+
+            *ip = str - buf;
+            break;
+        case 'f':
+            // 默认精度为3
+            // printk("1111\n");
+            // va_arg(args, double);
+            // printk("222\n");
+
+            if (precision < 0)
+                precision = 3;
+
+            str = write_float_point_num(str, va_arg(args, double), field_width, precision, flags);
+
+            break;
+
+        //对于不识别的控制符，直接输出
+        default:
+            *str++ = '%';
+            if (*fmt)
+                *str++ = *fmt;
+            else
+                --fmt;
+            break;
+        }
+    }
+    *str = '\0';
+
+    //返回缓冲区已有字符串的长度。
+    return str - buf;
+}
+
+static char *write_num(char *str, uint64_t num, int base, int field_width, int precision, int flags)
+{
+    /**
+     * @brief 将数字按照指定的要求转换成对应的字符串
+     *
+     * @param str 要返回的字符串
+     * @param num 要打印的数值
+     * @param base 基数
+     * @param field_width 区域宽度
+     * @param precision 精度
+     * @param flags 标志位
+     */
+
+    // 首先判断是否支持该进制
+    if (base < 2 || base > 36)
+        return 0;
+    char pad, sign, tmp_num[100];
+
+    const char *digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+    // 显示小写字母
+    if (flags & SMALL)
+        digits = "0123456789abcdefghijklmnopqrstuvwxyz";
+
+    if (flags & LEFT)
+        flags &= ~PAD_ZERO;
+    // 设置填充元素
+    pad = (flags & PAD_ZERO) ? '0' : ' ';
+
+    sign = 0;
+
+    if (flags & SIGN)
+    {
+        int64_t signed_num = (int64_t)num;
+        if (signed_num < 0)
+        {
+            sign = '-';
+            num = -signed_num;
+        }
+        else
+            num = signed_num;
+    }
+    else
+    {
+        // 设置符号
+        sign = (flags & PLUS) ? '+' : ((flags & SPACE) ? ' ' : 0);
+    }
+
+    // sign占用了一个宽度
+    if (sign)
+        --field_width;
+
+    if (flags & SPECIAL)
+        if (base == 16) // 0x占用2个位置
+            field_width -= 2;
+        else if (base == 8) // O占用一个位置
+            --field_width;
+
+    int js_num = 0; // 临时数字字符串tmp_num的长度
+
+    if (num == 0)
+        tmp_num[js_num++] = '0';
+    else
+    {
+        num = llabs(num);
+        //进制转换
+        while (num > 0)
+        {
+            tmp_num[js_num++] = digits[num % base]; // 注意这里，输出的数字，是小端对齐的。低位存低位
+            num /= base;
+        }
+    }
+
+    if (js_num > precision)
+        precision = js_num;
+
+    field_width -= precision;
+
+    // 靠右对齐
+    if (!(flags & (LEFT + PAD_ZERO)))
+        while (field_width-- > 0)
+            *str++ = ' ';
+
+    if (sign)
+        *str++ = sign;
+    if (flags & SPECIAL)
+        if (base == 16)
+        {
+            *str++ = '0';
+            *str++ = digits[33];
+        }
+        else if (base == 8)
+            *str++ = digits[24]; //注意这里是英文字母O或者o
+    if (!(flags & LEFT))
+        while (field_width-- > 0)
+            *str++ = pad;
+    while (js_num < precision)
+    {
+        --precision;
+        *str++ = '0';
+    }
+
+    while (js_num-- > 0)
+        *str++ = tmp_num[js_num];
+
+    while (field_width-- > 0)
+        *str++ = ' ';
+
+    return str;
+}
+
+static char *write_float_point_num(char *str, double num, int field_width, int precision, int flags)
+{
+    /**
+     * @brief 将浮点数按照指定的要求转换成对应的字符串
+     *
+     * @param str 要返回的字符串
+     * @param num 要打印的数值
+     * @param field_width 区域宽度
+     * @param precision 精度
+     * @param flags 标志位
+     */
+
+    char pad, sign, tmp_num_z[100], tmp_num_d[350];
+
+    const char *digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+    // 显示小写字母
+    if (flags & SMALL)
+        digits = "0123456789abcdefghijklmnopqrstuvwxyz";
+
+    // 设置填充元素
+    pad = (flags & PAD_ZERO) ? '0' : ' ';
+    sign = 0;
+    if (flags & SIGN && num < 0)
+    {
+        sign = '-';
+        num = -num;
+    }
+    else
+    {
+        // 设置符号
+        sign = (flags & PLUS) ? '+' : ((flags & SPACE) ? ' ' : 0);
+    }
+
+    // sign占用了一个宽度
+    if (sign)
+        --field_width;
+
+    int js_num_z = 0, js_num_d = 0;                                      // 临时数字字符串tmp_num_z tmp_num_d的长度
+    uint64_t num_z = (uint64_t)(num);                                    // 获取整数部分
+    uint64_t num_decimal = (uint64_t)(round((num - num_z) * precision)); // 获取小数部分
+
+    if (num == 0)
+        tmp_num_z[js_num_z++] = '0';
+    else
+    {
+        //存储整数部分
+        while (num_z > 0)
+        {
+            tmp_num_z[js_num_z++] = digits[num_z % 10]; // 注意这里，输出的数字，是小端对齐的。低位存低位
+            num_z /= 10;
+        }
+    }
+
+    while (num_decimal > 0)
+    {
+        tmp_num_d[js_num_d++] = digits[num_decimal % 10];
+        num_decimal /= 10;
+    }
+
+    field_width -= (precision + 1 + js_num_z);
+
+    // 靠右对齐
+    if (!(flags & LEFT))
+        while (field_width-- > 0)
+            *str++ = pad;
+
+    if (sign)
+        *str++ = sign;
+
+    // 输出整数部分
+    while (js_num_z-- > 0)
+        *str++ = tmp_num_z[js_num_z];
+
+    *str++ = '.';
+
+    // 输出小数部分
+    while (js_num_d-- > 0)
+        *str++ = tmp_num_d[js_num_d];
+
+    while (js_num_d < precision)
+    {
+        --precision;
+        *str++ = '0';
+    }
+
+    while (field_width-- > 0)
+        *str++ = ' ';
+
+    return str;
+}