Add: libc

libk/Makefile

@@ -0,0 +1,20 @@
+include ../Makefile.common
+
+
+OBJS	= \
+	  syscall.o \
+
+DEPS = $(OBJS:.o=.d)
+
+CPPFLAGS += -MMD -Iinclude
+CFLAGS += $(K_EXTRA_CFLAGS) -g -nostdlib
+LDFLAGS += -Wl,-Tkernel.lds
+LDLIBS =
+
+all: $(TARGET)
+	ar -rcs $(LIB).a *.o
+
+$(TARGET): $(OBJS)
+
+clean:
+	$(RM) $(OBJS) $(DEPS) $(TARGET) $(LIB).a

libk/syscall.c

@@ -0,0 +1,27 @@
+#include "syscall.h"
+
+int __syscall(int num, void *a0, void *a1, void *a2, void *a3, void *a4)
+{
+    int ret;
+    asm volatile("      \n \
+        mov %1, %%eax;  \n \
+        mov %2, %%ebx;  \n \
+        mov %3, %%ecx;  \n \
+        mov %4, %%edx;  \n \
+        mov %5, %%edi;  \n \
+        mov %6, %%esi;  \n \
+        int $48;        \n \
+        mov %%eax, %0" : "=m" (ret),
+                         "+m" (num),
+                         "+m" (a0),
+                         "+m" (a1),
+                         "+m" (a2),
+                         "+m" (a3),
+                         "+m" (a4));
+    return ret;
+}
+
+int write(int fd, char *buf, int count)
+{
+    return __syscall(1, (void *) fd, (void *) buf, (void *) count, (void *) 0, (void *) 0);
+}

libk/syscall.h

@@ -0,0 +1,7 @@
+#ifndef SYSCALL_H
+#define SYSCALL_H
+
+int __syscall(int num, void *a0, void *a1, void *a2, void *a3, void *a4);
+int write(int fd, char *buf, int count);
+
+#endif  /*  !SYSCALL_H */