From 1afa20dc557019204a575166004fb5fc30cc1d52 Mon Sep 17 00:00:00 2001
From: fslongjin <fslongjin@vip.qq.com>
Date: Sat, 22 Jan 2022 23:01:12 +0800
Subject: [PATCH] =?UTF-8?q?:new:=20=E6=A0=BC=E5=BC=8F=E5=8C=96=E8=BE=93?=
 =?UTF-8?q?=E5=87=BA=E4=B8=80=E4=B8=AA=E5=AD=97=E7=AC=A6=E4=B8=B2?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 kernel/printk.c | 41 +++++++++++++++++++++++++++++++++++++++++
 kernel/printk.h | 10 ++++++++++
 2 files changed, 51 insertions(+)

diff --git a/kernel/printk.c b/kernel/printk.c
index cecec45c..a6191a51 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -114,6 +114,7 @@ int vsprintf(char *buf, const char *fmt, va_list args)
             field_width = skip_and_atoi(&fmt);
 
         //获取小数精度
+        precision = -1;
         if (*fmt == '.')
         {
             ++fmt;
@@ -162,6 +163,46 @@ int vsprintf(char *buf, const char *fmt, va_list args)
                 ++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;
 
         default:
diff --git a/kernel/printk.h b/kernel/printk.h
index c09c8df9..c568ac4f 100644
--- a/kernel/printk.h
+++ b/kernel/printk.h
@@ -32,3 +32,13 @@ struct screen_info
 extern unsigned char font_ascii[256][16]; //导出ascii字体的bitmap（8*16大小）
 
 char buf[4096]; //vsprintf()的缓冲区
+
+
+/**
+     * 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
+     */
+int vsprintf(char *buf, const char *fmt, va_list args);
\ No newline at end of file