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343 行
9.6 KiB
343 行
9.6 KiB
#include <defs.h>
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#include <x86.h>
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#include <error.h>
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#include <stdio.h>
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#include <string.h>
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/* *
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* Space or zero padding and a field width are supported for the numeric
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* formats only.
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*
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* The special format %e takes an integer error code
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* and prints a string describing the error.
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* The integer may be positive or negative,
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* so that -E_NO_MEM and E_NO_MEM are equivalent.
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* */
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static const char * const error_string[MAXERROR + 1] = {
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[0] NULL,
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[E_UNSPECIFIED] "unspecified error",
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[E_BAD_PROC] "bad process",
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[E_INVAL] "invalid parameter",
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[E_NO_MEM] "out of memory",
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[E_NO_FREE_PROC] "out of processes",
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[E_FAULT] "segmentation fault",
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[E_INVAL_ELF] "invalid elf file",
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[E_KILLED] "process is killed",
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[E_PANIC] "panic failure",
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};
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/* *
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* printnum - print a number (base <= 16) in reverse order
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* @putch: specified putch function, print a single character
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* @putdat: used by @putch function
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* @num: the number will be printed
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* @base: base for print, must be in [1, 16]
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* @width: maximum number of digits, if the actual width is less than @width, use @padc instead
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* @padc: character that padded on the left if the actual width is less than @width
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* */
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static void
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printnum(void (*putch)(int, void*), void *putdat,
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unsigned long long num, unsigned base, int width, int padc) {
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unsigned long long result = num;
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unsigned mod = do_div(result, base);
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// first recursively print all preceding (more significant) digits
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if (num >= base) {
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printnum(putch, putdat, result, base, width - 1, padc);
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} else {
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// print any needed pad characters before first digit
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while (-- width > 0)
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putch(padc, putdat);
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}
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// then print this (the least significant) digit
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putch("0123456789abcdef"[mod], putdat);
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}
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/* *
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* getuint - get an unsigned int of various possible sizes from a varargs list
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* @ap: a varargs list pointer
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* @lflag: determines the size of the vararg that @ap points to
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* */
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static unsigned long long
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getuint(va_list *ap, int lflag) {
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if (lflag >= 2) {
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return va_arg(*ap, unsigned long long);
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}
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else if (lflag) {
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return va_arg(*ap, unsigned long);
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}
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else {
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return va_arg(*ap, unsigned int);
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}
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}
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/* *
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* getint - same as getuint but signed, we can't use getuint because of sign extension
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* @ap: a varargs list pointer
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* @lflag: determines the size of the vararg that @ap points to
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* */
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static long long
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getint(va_list *ap, int lflag) {
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if (lflag >= 2) {
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return va_arg(*ap, long long);
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}
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else if (lflag) {
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return va_arg(*ap, long);
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}
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else {
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return va_arg(*ap, int);
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}
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}
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/* *
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* printfmt - format a string and print it by using putch
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* @putch: specified putch function, print a single character
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* @putdat: used by @putch function
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* @fmt: the format string to use
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* */
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void
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printfmt(void (*putch)(int, void*), void *putdat, const char *fmt, ...) {
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va_list ap;
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va_start(ap, fmt);
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vprintfmt(putch, putdat, fmt, ap);
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va_end(ap);
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}
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/* *
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* vprintfmt - format a string and print it by using putch, it's called with a va_list
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* instead of a variable number of arguments
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* @putch: specified putch function, print a single character
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* @putdat: used by @putch function
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* @fmt: the format string to use
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* @ap: arguments for the format string
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*
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* Call this function if you are already dealing with a va_list.
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* Or you probably want printfmt() instead.
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* */
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void
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vprintfmt(void (*putch)(int, void*), void *putdat, const char *fmt, va_list ap) {
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register const char *p;
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register int ch, err;
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unsigned long long num;
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int base, width, precision, lflag, altflag;
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while (1) {
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while ((ch = *(unsigned char *)fmt ++) != '%') {
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if (ch == '\0') {
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return;
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}
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putch(ch, putdat);
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}
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// Process a %-escape sequence
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char padc = ' ';
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width = precision = -1;
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lflag = altflag = 0;
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reswitch:
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switch (ch = *(unsigned char *)fmt ++) {
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// flag to pad on the right
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case '-':
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padc = '-';
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goto reswitch;
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// flag to pad with 0's instead of spaces
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case '0':
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padc = '0';
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goto reswitch;
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// width field
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case '1' ... '9':
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for (precision = 0; ; ++ fmt) {
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precision = precision * 10 + ch - '0';
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ch = *fmt;
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if (ch < '0' || ch > '9') {
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break;
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}
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}
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goto process_precision;
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case '*':
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precision = va_arg(ap, int);
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goto process_precision;
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case '.':
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if (width < 0)
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width = 0;
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goto reswitch;
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case '#':
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altflag = 1;
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goto reswitch;
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process_precision:
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if (width < 0)
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width = precision, precision = -1;
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goto reswitch;
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// long flag (doubled for long long)
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case 'l':
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lflag ++;
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goto reswitch;
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// character
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case 'c':
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putch(va_arg(ap, int), putdat);
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break;
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// error message
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case 'e':
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err = va_arg(ap, int);
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if (err < 0) {
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err = -err;
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}
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if (err > MAXERROR || (p = error_string[err]) == NULL) {
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printfmt(putch, putdat, "error %d", err);
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}
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else {
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printfmt(putch, putdat, "%s", p);
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}
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break;
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// string
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case 's':
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if ((p = va_arg(ap, char *)) == NULL) {
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p = "(null)";
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}
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if (width > 0 && padc != '-') {
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for (width -= strnlen(p, precision); width > 0; width --) {
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putch(padc, putdat);
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}
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}
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for (; (ch = *p ++) != '\0' && (precision < 0 || -- precision >= 0); width --) {
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if (altflag && (ch < ' ' || ch > '~')) {
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putch('?', putdat);
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}
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else {
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putch(ch, putdat);
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}
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}
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for (; width > 0; width --) {
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putch(' ', putdat);
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}
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break;
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// (signed) decimal
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case 'd':
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num = getint(&ap, lflag);
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if ((long long)num < 0) {
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putch('-', putdat);
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num = -(long long)num;
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}
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base = 10;
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goto number;
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// unsigned decimal
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case 'u':
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num = getuint(&ap, lflag);
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base = 10;
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goto number;
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// (unsigned) octal
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case 'o':
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num = getuint(&ap, lflag);
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base = 8;
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goto number;
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// pointer
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case 'p':
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putch('0', putdat);
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putch('x', putdat);
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num = (unsigned long long)(uintptr_t)va_arg(ap, void *);
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base = 16;
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goto number;
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// (unsigned) hexadecimal
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case 'x':
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num = getuint(&ap, lflag);
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base = 16;
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number:
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printnum(putch, putdat, num, base, width, padc);
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break;
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// escaped '%' character
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case '%':
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putch(ch, putdat);
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break;
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// unrecognized escape sequence - just print it literally
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default:
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putch('%', putdat);
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for (fmt --; fmt[-1] != '%'; fmt --)
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/* do nothing */;
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break;
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}
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}
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}
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/* sprintbuf is used to save enough information of a buffer */
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struct sprintbuf {
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char *buf; // address pointer points to the first unused memory
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char *ebuf; // points the end of the buffer
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int cnt; // the number of characters that have been placed in this buffer
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};
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/* *
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* sprintputch - 'print' a single character in a buffer
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* @ch: the character will be printed
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* @b: the buffer to place the character @ch
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* */
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static void
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sprintputch(int ch, struct sprintbuf *b) {
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b->cnt ++;
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if (b->buf < b->ebuf) {
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*b->buf ++ = ch;
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}
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}
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/* *
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* snprintf - format a string and place it in a buffer
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* @str: the buffer to place the result into
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* @size: the size of buffer, including the trailing null space
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* @fmt: the format string to use
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* */
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int
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snprintf(char *str, size_t size, const char *fmt, ...) {
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va_list ap;
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int cnt;
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va_start(ap, fmt);
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cnt = vsnprintf(str, size, fmt, ap);
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va_end(ap);
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return cnt;
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}
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/* *
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* vsnprintf - format a string and place it in a buffer, it's called with a va_list
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* instead of a variable number of arguments
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* @str: the buffer to place the result into
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* @size: the size of buffer, including the trailing null space
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* @fmt: the format string to use
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* @ap: arguments for the format string
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*
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* The return value is the number of characters which would be generated for the
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* given input, excluding the trailing '\0'.
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*
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* Call this function if you are already dealing with a va_list.
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* Or you probably want snprintf() instead.
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* */
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int
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vsnprintf(char *str, size_t size, const char *fmt, va_list ap) {
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struct sprintbuf b = {str, str + size - 1, 0};
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if (str == NULL || b.buf > b.ebuf) {
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return -E_INVAL;
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}
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// print the string to the buffer
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vprintfmt((void*)sprintputch, &b, fmt, ap);
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// null terminate the buffer
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*b.buf = '\0';
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return b.cnt;
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}
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