1 files changed, 211 insertions, 0 deletions
diff --git a/sysroot/usr/lib/libc/stdio.c b/sysroot/usr/lib/libc/stdio.c
new file mode 100644
index 0000000..d0e7ad7
--- /dev/null
+++ b/sysroot/usr/lib/libc/stdio.c
@@ -0,0 +1,211 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdarg.h>
+
+int putchar(int character)
+{
+    char byte = (char)character;
+    if (write(1, &byte, 1) != 1)
+        return EOF;
+    return (unsigned char)byte;
+}
+
+int getchar(void)
+{
+    char byte;
+    if (read(0, &byte, 1) <= 0)
+        return EOF;
+    return (unsigned char)byte;
+}
+
+int puts(const char* string)
+{
+    (void)write(1, string, strlen(string));
+    (void)write(1, "\n", 1);
+    return 0;
+}
+
+static int format_unsigned(char* buffer, unsigned long value, int base, int upper)
+{
+    const char* digits = upper ? "0123456789ABCDEF" : "0123456789abcdef";
+    char temp[32];
+    int count = 0;
+    if (value == 0)
+        temp[count++] = '0';
+    while (value > 0)
+    {
+        temp[count++] = digits[value % (unsigned)base];
+        value /= (unsigned)base;
+    }
+    for (int i = 0; i < count; i++)
+        buffer[i] = temp[count - 1 - i];
+    return count;
+}
+
+static int format_signed(char* buffer, long value)
+{
+    int negative = value < 0;
+    unsigned long magnitude = negative ? (unsigned long)(-value) : (unsigned long)value;
+    int count = 0;
+    if (negative)
+        buffer[count++] = '-';
+    return count + format_unsigned(buffer + count, magnitude, 10, 0);
+}
+
+#define PRINTF_BUFFER 256
+
+// yoinked straight off open source
+int printf(const char* format, ...)
+{
+    char out[PRINTF_BUFFER];
+    int filled = 0;
+    int total = 0;
+    va_list args;
+    va_start(args, format);
+
+#define FLUSH()                          \
+    do {                                 \
+        if (filled > 0)                  \
+        {                                \
+            (void)write(1, out, filled); \
+            filled = 0;                  \
+        }                                \
+    } while (0)
+#define EMIT(ch)                      \
+    do {                              \
+        if (filled == PRINTF_BUFFER)  \
+            FLUSH();                  \
+        out[filled++] = (char)(ch);   \
+        total++;                      \
+    } while (0)
+
+    for (const char* cursor = format; *cursor; cursor++)
+    {
+        if (*cursor != '%')
+        {
+            EMIT(*cursor);
+            continue;
+        }
+
+        cursor++;
+        if (*cursor == '%')
+        {
+            EMIT('%');
+            continue;
+        }
+
+        int zero_pad = 0;
+        if (*cursor == '0')
+        {
+            zero_pad = 1;
+            cursor++;
+        }
+        int width = 0;
+        while (*cursor >= '0' && *cursor <= '9')
+        {
+            width = width * 10 + (*cursor - '0');
+            cursor++;
+        }
+        int is_long = 0;
+        while (*cursor == 'l')
+        {
+            is_long = 1;
+            cursor++;
+        }
+
+        char conversion = *cursor;
+        if (conversion == 's')
+        {
+            const char* string = va_arg(args, const char*);
+            if (!string)
+                string = "(null)";
+            int length = (int)strlen(string);
+            for (int i = length; i < width; i++)
+                EMIT(' ');
+            for (int i = 0; i < length; i++)
+                EMIT(string[i]);
+            continue;
+        }
+        if (conversion == 'c')
+        {
+            int character = va_arg(args, int);
+            for (int i = 1; i < width; i++)
+                EMIT(' ');
+            EMIT(character);
+            continue;
+        }
+
+        char number[34];
+        int length = 0;
+        if (conversion == 'd' || conversion == 'i')
+        {
+            long value = is_long ? va_arg(args, long) : (long)va_arg(args, int);
+            length = format_signed(number, value);
+        }
+        else if (conversion == 'u')
+        {
+            unsigned long value = is_long ? va_arg(args, unsigned long) : (unsigned long)va_arg(args, unsigned int);
+            length = format_unsigned(number, value, 10, 0);
+        }
+        else if (conversion == 'x' || conversion == 'X')
+        {
+            unsigned long value = is_long ? va_arg(args, unsigned long) : (unsigned long)va_arg(args, unsigned int);
+            length = format_unsigned(number, value, 16, conversion == 'X');
+        }
+        else if (conversion == 'p')
+        {
+            unsigned long value = (unsigned long)va_arg(args, void*);
+            EMIT('0');
+            EMIT('x');
+            length = format_unsigned(number, value, 16, 0);
+        }
+        else
+        {
+            EMIT('%');
+            EMIT(conversion);
+            continue;
+        }
+
+        for (int i = length; i < width; i++)
+            EMIT(zero_pad ? '0' : ' ');
+        for (int i = 0; i < length; i++)
+            EMIT(number[i]);
+    }
+
+    FLUSH();
+    va_end(args);
+    return total;
+
+#undef EMIT
+#undef FLUSH
+}
+
+int readline(char* buffer, int max_length)
+{
+    int length = 0;
+    for (;;)
+    {
+        char character;
+        if (read(0, &character, 1) <= 0)
+            break;
+        if (character == '\n')
+            break;
+        if (character == '\b')
+        {
+            if (length > 0)
+            {
+                length--;
+                (void)write(1, "\b \b", 3);
+            }
+            continue;
+        }
+        if (length < max_length - 1)
+        {
+            buffer[length++] = character;
+            (void)write(1, &character, 1);
+        }
+    }
+    buffer[length] = 0;
+    return length;
+}