详见：嵌入式大讲堂
f_gets：
1 /*-----------------------------------------------------------------------*/
2 /* Get a string from the file */
3 /*-----------------------------------------------------------------------*/
4 TCHAR* f_gets (
5 TCHAR* buff, /* Pointer to the string buffer to read */
6 int len, /* Size of string buffer (characters) */
7 FIL* fil /* Pointer to the file object */
8 )
9 {
10 int n = 0;
11 TCHAR c, *p = buff;
12 BYTE s[2];
13 UINT rc;
14
15
16 while (n < len - 1) { /* Read bytes until buffer gets filled */
17 f_read(fil, s, 1, &rc);
18 if (rc != 1) break; /* Break on EOF or error */
19 c = s[0];
20 #if _LFN_UNICODE /* Read a character in UTF-8 encoding */
21 if (c >= 0x80) {
22 if (c < 0xC0) continue; /* Skip stray trailer */
23 if (c < 0xE0) { /* Two-byte sequense */
24 f_read(fil, s, 1, &rc);
25 if (rc != 1) break;
26 c = ((c & 0x1F) << 6) | (s[0] & 0x3F);
27 if (c < 0x80) c = ‘?‘;
28 } else {
29 if (c < 0xF0) { /* Three-byte sequense */
30 f_read(fil, s, 2, &rc);
31 if (rc != 2) break;
32 c = (c << 12) | ((s[0] & 0x3F) << 6) | (s[1] & 0x3F);
33 if (c < 0x800) c = ‘?‘;
34 } else { /* Reject four-byte sequense */
35 c = ‘?‘;
36 }
37 }
38 }
39 #endif
40 #if _USE_STRFUNC >= 2
41 if (c == ‘\r‘) continue; /* Strip ‘\r‘ */
42 #endif
43 *p++ = c;
44 n++;
45 if (c == ‘\n‘) break; /* Break on EOL */
46 }
47 *p = 0;
48 return n ? buff : 0; /* When no data read (eof or error), return with error. */
49 }
函数功能：f_gets从文件中读取一个字符串。
描述：
f_gets函数当_USE_STRFUNC == 1或者_USE_STRFUNC == 2时可用。如果_USE_STRFUNC == 2，文件中包含的‘\r‘则被去除。
f_gets函数是f_read的一个封装函数。当读取到‘\n‘、文件结束或缓冲区被填冲了Size - 1个字符时，读操作结束。读取的字符串以‘\0‘结束。当文件结束或读操作中发生了任何错误，f_gets()返回一个空字符串。可以使用宏f_eof()和f_error()检查EOF和错误状态。
f_putc：
1 /*-----------------------------------------------------------------------*/
2 /* Put a character to the file */
3 /*-----------------------------------------------------------------------*/
4 int f_putc (
5 TCHAR c, /* A character to be output */
6 FIL* fil /* Pointer to the file object */
7 )
8 {
9 UINT bw, btw;
10 BYTE s[3];
11
12
13 #if _USE_STRFUNC >= 2
14 if (c == ‘\n‘) f_putc (‘\r‘, fil); /* LF -> CRLF conversion */
15 #endif
16
17 #if _LFN_UNICODE /* Write the character in UTF-8 encoding */
18 if (c < 0x80) { /* 7-bit */
19 s[0] = (BYTE)c;
20 btw = 1;
21 } else {
22 if (c < 0x800) { /* 11-bit */
23 s[0] = (BYTE)(0xC0 | (c >> 6));
24 s[1] = (BYTE)(0x80 | (c & 0x3F));
25 btw = 2;
26 } else { /* 16-bit */
27 s[0] = (BYTE)(0xE0 | (c >> 12));
28 s[1] = (BYTE)(0x80 | ((c >> 6) & 0x3F));
29 s[2] = (BYTE)(0x80 | (c & 0x3F));
30 btw = 3;
31 }
32 }
33 #else /* Write the character without conversion */
34 s[0] = (BYTE)c;
35 btw = 1;
36 #endif
37 f_write(fil, s, btw, &bw); /* Write the char to the file */
38 return (bw == btw) ? 1 : EOF; /* Return the result */
39 }
函数功能：f_putc函数向文件中写入一个字符。
描述：
f_putc函数当(_FS_READONLY == 0)&&(_USE_STRFUNC == 1 || _USE_STRFUNC == 2)时可用。当_USE_STRFUNC == 2时，字符‘\n‘被转换为"\r\n"写入文件中。
f_putc函数是f_write的一个封装函数。
f_puts：
1 /*-----------------------------------------------------------------------*/
2 /* Put a string to the file */
3 /*-----------------------------------------------------------------------*/
4 int f_puts (
5 const TCHAR* str, /* Pointer to the string to be output */
6 FIL* fil /* Pointer to the file object */
7 )
8 {
9 int n;
10
11
12 for (n = 0; *str; str++, n++) {
13 if (f_putc(*str, fil) == EOF) return EOF;
14 }
15 return n;
16 }
函数功能：f_puts函数向文件中写入一个字符串。
描述：
f_puts()当(_FS_READONLY == 0)&&(_USE_STRFUNC == 1 || _USE_STRFUNC == 2)时可用。当_USE_STRFUNC == 2时，字符串中的‘\n‘被转换为"\r\n"写入文件中。
f_puts()是f_putc()的一个封装函数。
f_printf：
1 /*-----------------------------------------------------------------------*/
2 /* Put a formatted string to the file */
3 /*-----------------------------------------------------------------------*/
4 int f_printf (
5 FIL* fil, /* Pointer to the file object */
6 const TCHAR* str, /* Pointer to the format string */
7 ... /* Optional arguments... */
8 )
9 {
10 va_list arp;
11 BYTE f, r;
12 UINT i, j, w;
13 ULONG v;
14 TCHAR c, d, s[16], *p;
15 int res, chc, cc;
16
17
18 va_start(arp, str);
19
20 for (cc = res = 0; cc != EOF; res += cc) {
21 c = *str++;
22 if (c == 0) break; /* End of string */
23 if (c != ‘%‘) { /* Non escape character */
24 cc = f_putc(c, fil);
25 if (cc != EOF) cc = 1;
26 continue;
27 }
28 w = f = 0;
29 c = *str++;
30 if (c == ‘0‘) { /* Flag: ‘0‘ padding */
31 f = 1; c = *str++;
32 } else {
33 if (c == ‘-‘) { /* Flag: left justified */
34 f = 2; c = *str++;
35 }
36 }
37 while (IsDigit(c)) { /* Precision */
38 w = w * 10 + c - ‘0‘;
39 c = *str++;
40 }
41 if (c == ‘l‘ || c == ‘L‘) { /* Prefix: Size is long int */
42 f |= 4; c = *str++;
43 }
44 if (!c) break;
45 d = c;
46 if (IsLower(d)) d -= 0x20;
47 switch (d) { /* Type is... */
48 case ‘S‘ : /* String */
49 p = va_arg(arp, TCHAR*);
50 for (j = 0; p[j]; j++) ;
51 chc = 0;
52 if (!(f & 2)) {
53 while (j++ < w) chc += (cc = f_putc(‘ ‘, fil));
54 }
55 chc += (cc = f_puts(p, fil));
56 while (j++ < w) chc += (cc = f_putc(‘ ‘, fil));
57 if (cc != EOF) cc = chc;
58 continue;
59 case ‘C‘ : /* Character */
60 cc = f_putc((TCHAR)va_arg(arp, int), fil); continue;
61 case ‘B‘ : /* Binary */
62 r = 2; break;
63 case ‘O‘ : /* Octal */
64 r = 8; break;
65 case ‘D‘ : /* Signed decimal */
66 case ‘U‘ : /* Unsigned decimal */
67 r = 10; break;
68 case ‘X‘ : /* Hexdecimal */
69 r = 16; break;
70 default: /* Unknown type (passthrough) */
71 cc = f_putc(c, fil); continue;
72 }
73
74 /* Get an argument and put it in numeral */
75 v = (f & 4) ? (ULONG)va_arg(arp, long) : ((d == ‘D‘) ? (ULONG)(long)va_arg(arp, int) : (ULONG)va_arg(arp, unsigned int));
76 if (d == ‘D‘ && (v & 0x80000000)) {
77 v = 0 - v;
78 f |= 8;
79 }
80 i = 0;
81 do {
82 d = (TCHAR)(v % r); v /= r;
83 if (d > 9) d += (c == ‘x‘) ? 0x27 : 0x07;
84 s[i++] = d + ‘0‘;
85 } while (v && i < sizeof(s) / sizeof(s[0]));
86 if (f & 8) s[i++] = ‘-‘;
87 j = i; d = (f & 1) ? ‘0‘ : ‘ ‘;
88 res = 0;
89 while (!(f & 2) && j++ < w) res += (cc = f_putc(d, fil));
90 do res += (cc = f_putc(s[--i], fil)); while(i);
91 while (j++ < w) res += (cc = f_putc(‘ ‘, fil));
92 if (cc != EOF) cc = res;
93 }
94
95 va_end(arp);
96 return (cc == EOF) ? cc : res;
97 }
函数功能：f_printf函数向文件中写入一个格式化字符串。
描述：
f_printf函数当(_FS_READONLY == 0)&&(_USE_STRFUNC == 1 || _USE_STRFUNC == 2)时可用。当_USE_STRFUNC == 2时，包含在格式化字符串中的‘\n‘将被转换成"\r\n"写入文件中。
f_printf函数是f_putc和f_puts的一个封装函数。
例：
1 f_gets(buf, NUM, &fil); // 从文件中读取一个字符串的前 NUM个字符 2 f_putc(ch, &fil); // 向文件中写入一个字符 3 f_puts((char *)buffer, &fil); // 向文件内写入一个字符串 4 5 f_printf(&fil, "%6d", -200); /* " -200" */ 6 f_printf(&fil, "%02u", 5); /* "05" */ 7 f_printf(&fil, "%ld", 12345678L); /* "12345678" */ 8 f_printf(&fil, "%08lX", 1194684UL); /* "00123ABC" */ 9 f_printf(&fil, "%s", "String"); /* "String" */ 10 f_printf(&fil, "%c", ‘a‘); /* "a" */
FATFS 初学之 f_gets/ f_putc/ f_puts/ f_printf
时间： 2024-10-05 10:56:16