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    Subject[x86 setup 20/33] Console-writing code for the new x86 setup code
    Date
    From: H. Peter Anvin <hpa@zytor.com>

    This implements writing text to the console, including printf().

    Signed-off-by: H. Peter Anvin <hpa@zytor.com>
    ---
    arch/i386/boot/printf.c | 307 +++++++++++++++++++++++++++++++++++++++++++++++
    arch/i386/boot/tty.c | 112 +++++++++++++++++
    2 files changed, 419 insertions(+), 0 deletions(-)
    create mode 100644 arch/i386/boot/printf.c
    create mode 100644 arch/i386/boot/tty.c
    diff --git a/arch/i386/boot/printf.c b/arch/i386/boot/printf.c
    new file mode 100644
    index 0000000..1a09f93
    --- /dev/null
    +++ b/arch/i386/boot/printf.c
    @@ -0,0 +1,307 @@
    +/* -*- linux-c -*- ------------------------------------------------------- *
    + *
    + * Copyright (C) 1991, 1992 Linus Torvalds
    + * Copyright 2007 rPath, Inc. - All Rights Reserved
    + *
    + * This file is part of the Linux kernel, and is made available under
    + * the terms of the GNU General Public License version 2.
    + *
    + * ----------------------------------------------------------------------- */
    +
    +/*
    + * arch/i386/boot/printf.c
    + *
    + * Oh, it's a waste of space, but oh-so-yummy for debugging. This
    + * version of printf() does not include 64-bit support. "Live with
    + * it."
    + *
    + */
    +
    +#include "boot.h"
    +
    +static int skip_atoi(const char **s)
    +{
    + int i = 0;
    +
    + while (isdigit(**s))
    + i = i * 10 + *((*s)++) - '0';
    + return i;
    +}
    +
    +#define ZEROPAD 1 /* pad with zero */
    +#define SIGN 2 /* unsigned/signed long */
    +#define PLUS 4 /* show plus */
    +#define SPACE 8 /* space if plus */
    +#define LEFT 16 /* left justified */
    +#define SPECIAL 32 /* 0x */
    +#define LARGE 64 /* use 'ABCDEF' instead of 'abcdef' */
    +
    +#define do_div(n,base) ({ \
    +int __res; \
    +__res = ((unsigned long) n) % (unsigned) base; \
    +n = ((unsigned long) n) / (unsigned) base; \
    +__res; })
    +
    +static char *number(char *str, long num, int base, int size, int precision,
    + int type)
    +{
    + char c, sign, tmp[66];
    + const char *digits = "0123456789abcdefghijklmnopqrstuvwxyz";
    + int i;
    +
    + if (type & LARGE)
    + digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    + if (type & LEFT)
    + type &= ~ZEROPAD;
    + if (base < 2 || base > 36)
    + return 0;
    + c = (type & ZEROPAD) ? '0' : ' ';
    + sign = 0;
    + if (type & SIGN) {
    + if (num < 0) {
    + sign = '-';
    + num = -num;
    + size--;
    + } else if (type & PLUS) {
    + sign = '+';
    + size--;
    + } else if (type & SPACE) {
    + sign = ' ';
    + size--;
    + }
    + }
    + if (type & SPECIAL) {
    + if (base == 16)
    + size -= 2;
    + else if (base == 8)
    + size--;
    + }
    + i = 0;
    + if (num == 0)
    + tmp[i++] = '0';
    + else
    + while (num != 0)
    + tmp[i++] = digits[do_div(num, base)];
    + if (i > precision)
    + precision = i;
    + size -= precision;
    + if (!(type & (ZEROPAD + LEFT)))
    + while (size-- > 0)
    + *str++ = ' ';
    + if (sign)
    + *str++ = sign;
    + if (type & SPECIAL) {
    + if (base == 8)
    + *str++ = '0';
    + else if (base == 16) {
    + *str++ = '0';
    + *str++ = digits[33];
    + }
    + }
    + if (!(type & LEFT))
    + while (size-- > 0)
    + *str++ = c;
    + while (i < precision--)
    + *str++ = '0';
    + while (i-- > 0)
    + *str++ = tmp[i];
    + while (size-- > 0)
    + *str++ = ' ';
    + return str;
    +}
    +
    +int vsprintf(char *buf, const char *fmt, va_list args)
    +{
    + int len;
    + unsigned long num;
    + int i, base;
    + char *str;
    + const char *s;
    +
    + int flags; /* flags to number() */
    +
    + int field_width; /* width of output field */
    + int precision; /* min. # of digits for integers; max
    + number of chars for from string */
    + int qualifier; /* 'h', 'l', or 'L' for integer fields */
    +
    + for (str = buf; *fmt; ++fmt) {
    + if (*fmt != '%') {
    + *str++ = *fmt;
    + continue;
    + }
    +
    + /* process flags */
    + flags = 0;
    + repeat:
    + ++fmt; /* this also skips first '%' */
    + switch (*fmt) {
    + case '-':
    + flags |= LEFT;
    + goto repeat;
    + case '+':
    + flags |= PLUS;
    + goto repeat;
    + case ' ':
    + flags |= SPACE;
    + goto repeat;
    + case '#':
    + flags |= SPECIAL;
    + goto repeat;
    + case '0':
    + flags |= ZEROPAD;
    + goto repeat;
    + }
    +
    + /* get field width */
    + field_width = -1;
    + if (isdigit(*fmt))
    + field_width = skip_atoi(&fmt);
    + else if (*fmt == '*') {
    + ++fmt;
    + /* it's the next argument */
    + field_width = va_arg(args, int);
    + if (field_width < 0) {
    + field_width = -field_width;
    + flags |= LEFT;
    + }
    + }
    +
    + /* get the precision */
    + precision = -1;
    + if (*fmt == '.') {
    + ++fmt;
    + if (isdigit(*fmt))
    + precision = skip_atoi(&fmt);
    + else if (*fmt == '*') {
    + ++fmt;
    + /* it's the next argument */
    + precision = va_arg(args, int);
    + }
    + if (precision < 0)
    + precision = 0;
    + }
    +
    + /* get the conversion qualifier */
    + qualifier = -1;
    + if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L') {
    + qualifier = *fmt;
    + ++fmt;
    + }
    +
    + /* default base */
    + base = 10;
    +
    + switch (*fmt) {
    + case 'c':
    + if (!(flags & LEFT))
    + while (--field_width > 0)
    + *str++ = ' ';
    + *str++ = (unsigned char)va_arg(args, int);
    + while (--field_width > 0)
    + *str++ = ' ';
    + continue;
    +
    + case 's':
    + s = va_arg(args, char *);
    + len = strnlen(s, precision);
    +
    + if (!(flags & LEFT))
    + while (len < field_width--)
    + *str++ = ' ';
    + for (i = 0; i < len; ++i)
    + *str++ = *s++;
    + while (len < field_width--)
    + *str++ = ' ';
    + continue;
    +
    + case 'p':
    + if (field_width == -1) {
    + field_width = 2 * sizeof(void *);
    + flags |= ZEROPAD;
    + }
    + str = number(str,
    + (unsigned long)va_arg(args, void *), 16,
    + field_width, precision, flags);
    + continue;
    +
    + case 'n':
    + if (qualifier == 'l') {
    + long *ip = va_arg(args, long *);
    + *ip = (str - buf);
    + } else {
    + int *ip = va_arg(args, int *);
    + *ip = (str - buf);
    + }
    + continue;
    +
    + case '%':
    + *str++ = '%';
    + continue;
    +
    + /* integer number formats - set up the flags and "break" */
    + case 'o':
    + base = 8;
    + break;
    +
    + case 'X':
    + flags |= LARGE;
    + case 'x':
    + base = 16;
    + break;
    +
    + case 'd':
    + case 'i':
    + flags |= SIGN;
    + case 'u':
    + break;
    +
    + default:
    + *str++ = '%';
    + if (*fmt)
    + *str++ = *fmt;
    + else
    + --fmt;
    + continue;
    + }
    + if (qualifier == 'l')
    + num = va_arg(args, unsigned long);
    + else if (qualifier == 'h') {
    + num = (unsigned short)va_arg(args, int);
    + if (flags & SIGN)
    + num = (short)num;
    + } else if (flags & SIGN)
    + num = va_arg(args, int);
    + else
    + num = va_arg(args, unsigned int);
    + str = number(str, num, base, field_width, precision, flags);
    + }
    + *str = '\0';
    + return str - buf;
    +}
    +
    +int sprintf(char *buf, const char *fmt, ...)
    +{
    + va_list args;
    + int i;
    +
    + va_start(args, fmt);
    + i = vsprintf(buf, fmt, args);
    + va_end(args);
    + return i;
    +}
    +
    +int printf(const char *fmt, ...)
    +{
    + char printf_buf[1024];
    + va_list args;
    + int printed;
    +
    + va_start(args, fmt);
    + printed = vsprintf(printf_buf, fmt, args);
    + va_end(args);
    +
    + puts(printf_buf);
    +
    + return printed;
    +}
    diff --git a/arch/i386/boot/tty.c b/arch/i386/boot/tty.c
    new file mode 100644
    index 0000000..a8db787
    --- /dev/null
    +++ b/arch/i386/boot/tty.c
    @@ -0,0 +1,112 @@
    +/* -*- linux-c -*- ------------------------------------------------------- *
    + *
    + * Copyright (C) 1991, 1992 Linus Torvalds
    + * Copyright 2007 rPath, Inc. - All Rights Reserved
    + *
    + * This file is part of the Linux kernel, and is made available under
    + * the terms of the GNU General Public License version 2.
    + *
    + * ----------------------------------------------------------------------- */
    +
    +/*
    + * arch/i386/boot/tty.c
    + *
    + * Very simple screen I/O
    + * XXX: Probably should add very simple serial I/O?
    + */
    +
    +#include "boot.h"
    +
    +/*
    + * These functions are in .inittext so they can be used to signal
    + * error during initialization.
    + */
    +
    +void __attribute__((section(".inittext"))) putchar(int ch)
    +{
    + unsigned char c = ch;
    +
    + if (c == '\n')
    + putchar('\r'); /* \n -> \r\n */
    +
    + /* int $0x10 is known to have bugs involving touching registers
    + it shouldn't. Be extra conservative... */
    + asm volatile("pushal; int $0x10; popal"
    + : : "b" (0x0007), "c" (0x0001), "a" (0x0e00|ch));
    +}
    +
    +void __attribute__((section(".inittext"))) puts(const char *str)
    +{
    + int n = 0;
    + while (*str) {
    + putchar(*str++);
    + n++;
    + }
    +}
    +
    +/*
    + * Read the CMOS clock through the BIOS, and return the
    + * seconds in BCD.
    + */
    +
    +static u8 gettime(void)
    +{
    + u16 ax = 0x0200;
    + u16 cx, dx;
    +
    + asm("int $0x1a"
    + : "+a" (ax), "=c" (cx), "=d" (dx)
    + : : "ebx", "esi", "edi");
    +
    + return dx >> 8;
    +}
    +
    +/*
    + * Read from the keyboard
    + */
    +int getchar(void)
    +{
    + u16 ax = 0;
    + asm("int $0x16" : "+a" (ax));
    +
    + return ax & 0xff;
    +}
    +
    +static int kbd_pending(void)
    +{
    + u8 pending;
    + asm("int $0x16; setnz %0"
    + : "=rm" (pending)
    + : "a" (0x0100));
    + return pending;
    +}
    +
    +void kbd_flush(void)
    +{
    + for (;;) {
    + if (!kbd_pending())
    + break;
    + getchar();
    + }
    +}
    +
    +int getchar_timeout(void)
    +{
    + int cnt = 30;
    + int t0, t1;
    +
    + t0 = gettime();
    +
    + while (cnt) {
    + if (kbd_pending())
    + return getchar();
    +
    + t1 = gettime();
    + if (t0 != t1) {
    + cnt--;
    + t0 = t1;
    + }
    + }
    +
    + return 0; /* Timeout! */
    +}
    --
    1.5.2.2
    -
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