...

src/runtime/.gitignore

@@ -1 +1 @@
-runtime.o
+*.o

src/runtime/makefile

@@ -1,5 +1,5 @@
-runtime:
-	cc -c runtime.c
+x86_64:
+	gcc -nostdlib -ffreestanding -c platform/x86_64.s runtime.c
 
 clean:
 	rm runtime.o

src/runtime/platform/x86_64.s

@@ -0,0 +1,17 @@
+.intel_syntax noprefix
+
+.text
+.globl nub_write_string
+# void nub_write_string(const char* str)
+nub_write_string:
+    mov rsi, rdi
+    mov rdi, 1
+    mov rax, 1
+    syscall
+
+.text
+.globl nub_exit
+# void nub_exit(int code)
+nub_exit:
+    mov rax, 60
+    syscall

src/runtime/runtime.c

@@ -1,16 +1,17 @@
 #include <stdint.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/syscall.h>
-#include <syscall.h>
-#include <unistd.h>
 
 #define NUB_PANIC_ERROR_CODE 101
 
-uint64_t nub_cstring_length(char* string)
+extern void nub_write_string(const char* str);
+extern void nub_exit(int code);
+
+uint64_t nub_cstring_length(const char* string)
 {
-    return strlen(string);
+    uint64_t len = 0;
+    while (string[len] != '\0') {
+        len++;
+    }
+    return len;
 }
 
 uint64_t nub_string_length()
@@ -18,32 +19,37 @@ uint64_t nub_string_length()
     return 0;
 }
 
-void nub_memcpy(void* source, void* destination, uint64_t length)
+void nub_memcpy(uint8_t* source, uint8_t* destination, uint64_t length)
 {
-    memcpy(destination, source, length);
+    for (uint64_t i = 0; i < length; i++) {
+        destination[i] = source[i];
+    }
 }
 
-void nub_memset(void* destination, int value, uint64_t count)
+void nub_memset(uint8_t* destination, uint8_t value, uint64_t count)
 {
-    memset(destination, value, count);
+    for (uint64_t i = 0; i < count; i++) {
+        destination[i] = value;
+    }
 }
 
 void nub_panic_array_oob()
 {
-    puts("Array out of bounds");
-    exit(NUB_PANIC_ERROR_CODE);
+    nub_write_string("Array out of bounds\n");
+    nub_exit(NUB_PANIC_ERROR_CODE);
 }
 
 void nub_panic_oom()
 {
-    puts("Out of memory");
-    exit(NUB_PANIC_ERROR_CODE);
+    nub_write_string("Out of memory\n");
+    nub_exit(NUB_PANIC_ERROR_CODE);
 }
 
-extern int64_t main();
+extern int main();
 
-void _start()
+__attribute__((noreturn)) void _start()
 {
-    int64_t exit_code = main();
-    exit(exit_code);
+    int exit_code = main();
+    nub_exit(exit_code);
+    __builtin_unreachable();
 }