1 files changed, 97 insertions, 0 deletions
diff --git a/user/user.h b/user/user.h
new file mode 100644
index 0000000..676326b
--- /dev/null
+++ b/user/user.h
@@ -0,0 +1,97 @@
+// shared syscall stubs + tiny helpers for revel ring 3 programs
+
+static long sys_write(const char* buffer, unsigned long length)
+{
+    long result;
+    __asm__ volatile("int $0x80" : "=a"(result) : "a"(1L), "D"(buffer), "S"(length) : "memory");
+    return result;
+}
+
+static long sys_read(void)
+{
+    long result;
+    __asm__ volatile("int $0x80" : "=a"(result) : "a"(2L) : "memory");
+    return result;
+}
+
+static void sys_exit(long code)
+{
+    __asm__ volatile("int $0x80" : : "a"(0L), "D"(code) : "memory");
+    for (;;);
+}
+
+static long sys_fs_size(const char* name)
+{
+    long result;
+    __asm__ volatile("int $0x80" : "=a"(result) : "a"(4L), "D"(name) : "memory");
+    return result;
+}
+
+static long sys_fs_read(const char* name, unsigned long offset, char* buffer, unsigned long length)
+{
+    long result;
+    __asm__ volatile("int $0x80"
+                     : "=a"(result)
+                     : "a"(5L), "D"(name), "S"(offset), "d"(buffer), "c"(length)
+                     : "memory");
+    return result;
+}
+
+static void put(const char* string)
+{
+    unsigned long length = 0;
+    while (string[length])
+        length++;
+    sys_write(string, length);
+}
+
+static int read_line(char* buffer, int max_length)
+{
+    int length = 0;
+    for (;;)
+    {
+        char character = (char)sys_read();
+        if (character == '\n')
+            break;
+        if (character == '\b')
+        {
+            if (length > 0)
+            {
+                length--;
+                sys_write("\b \b", 3);
+            }
+            continue;
+        }
+        if (length < max_length - 1)
+        {
+            buffer[length++] = character;
+            sys_write(&character, 1);
+        }
+    }
+    buffer[length] = 0;
+    return length;
+}
+
+static void put_int(long value)
+{
+    char buffer[21];
+    int length = 0;
+    int negative = value < 0;
+    unsigned long magnitude = negative ? (unsigned long)(-value) : (unsigned long)value;
+    if (magnitude == 0)
+        buffer[length++] = '0';
+    while (magnitude > 0)
+    {
+        buffer[length++] = (char)('0' + magnitude % 10);
+        magnitude /= 10;
+    }
+    if (negative)
+        buffer[length++] = '-';
+    for (int left = 0, right = length - 1; left < right; left++, right--)
+    {
+        char swap = buffer[left];
+        buffer[left] = buffer[right];
+        buffer[right] = swap;
+    }
+    sys_write(buffer, length);
+}