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/***************************************************************************
* Copyright (c) 2026 10xEngineers
*
* This program and the accompanying materials are made available under the
* terms of the MIT License which is available at
* https://opensource.org/licenses/MIT.
*
* SPDX-License-Identifier: MIT
**************************************************************************/
/* Minimal printf/puts for RISC-V QEMU virt regression tests.
Avoids linking newlib's stdio which is compiled with mcmodel=medlow
and causes relocation overflow on RV64 (DRAM at 0x80000000).
Only the format specifiers used by the test suite are supported:
%s, %d, %u, %lu, %ld, %%, and plain strings. */
#include <stdarg.h>
#include <stddef.h>
extern int _write(int fd, const char *buf, int count);
static void print_str(const char *s)
{
const char *p = s;
while (*p)
p++;
_write(1, s, (int)(p - s));
}
static void print_unsigned(unsigned long val)
{
char buf[21];
int i = 0;
if (val == 0)
{
_write(1, "0", 1);
return;
}
while (val > 0)
{
buf[i++] = (char)('0' + (int)(val % 10u));
val /= 10u;
}
/* Reverse. */
for (int j = i - 1; j >= 0; j--)
_write(1, &buf[j], 1);
}
static void print_hex(unsigned long val)
{
static const char hex[] = "0123456789abcdef";
char buf[17];
int i = 0;
if (val == 0)
{
_write(1, "0", 1);
return;
}
while (val > 0)
{
buf[i++] = hex[val & 0xfu];
val >>= 4;
}
for (int j = i - 1; j >= 0; j--)
_write(1, &buf[j], 1);
}
static void print_signed(long val)
{
if (val < 0)
{
_write(1, "-", 1);
print_unsigned((unsigned long)(-val));
}
else
{
print_unsigned((unsigned long)val);
}
}
int printf(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
const char *p = fmt;
const char *seg = p;
while (*p)
{
if (*p == '%')
{
/* Flush preceding literal segment. */
if (p > seg)
_write(1, seg, (int)(p - seg));
p++;
/* Check for 'l' length modifier. */
int is_long = 0;
if (*p == 'l')
{
is_long = 1;
p++;
}
switch (*p)
{
case 's':
print_str(va_arg(ap, const char *));
break;
case 'd':
if (is_long)
print_signed(va_arg(ap, long));
else
print_signed((long)va_arg(ap, int));
break;
case 'u':
if (is_long)
print_unsigned(va_arg(ap, unsigned long));
else
print_unsigned((unsigned long)va_arg(ap, unsigned int));
break;
case 'x':
if (is_long)
print_hex(va_arg(ap, unsigned long));
else
print_hex((unsigned long)va_arg(ap, unsigned int));
break;
case '%':
_write(1, "%", 1);
break;
default:
/* Unknown specifier — print as-is. */
_write(1, "%", 1);
if (is_long)
_write(1, "l", 1);
_write(1, p, 1);
break;
}
p++;
seg = p;
}
else
{
p++;
}
}
/* Flush remaining literal segment. */
if (p > seg)
_write(1, seg, (int)(p - seg));
va_end(ap);
return 0;
}
int puts(const char *s)
{
print_str(s);
_write(1, "\n", 1);
return 0;
}
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