Added setjmp.h

libc/include/setjmp.h

@@ -0,0 +1,13 @@
+#ifndef _SETJMP_H
+#define _SETJMP_H
+
+typedef struct {
+    void* _bp;  // Base pointer
+    void* _sp;  // Stack pointer
+    void* _pc;  // Program counter
+} jmp_buf;
+
+int setjmp(jmp_buf env);
+void longjmp(jmp_buf env, int value);
+
+#endif

libc/setjmp/setjmp.c

@@ -0,0 +1,26 @@
+#include <setjmp.h>
+
+int setjmp(jmp_buf env) {
+    __asm__ volatile (
+        "mov %%ebp, %0\n"   // Save BP
+        "mov %%esp, %1\n"   // Save SP
+        "call 1f\n"         // Call label to push PC to the stack
+        "pop %2\n"          // Save PC
+        : "=m"(env._bp), "=m"(env._sp), "=m"(env._pc)  // Locations
+    );
+    return 0;
+}
+
+void longjmp(jmp_buf env, int value) {
+    if (val == 0) return;
+
+    __asm__ volatile (
+        "mov %0, %%ebp\n"   // Restore BP
+        "mov %1, %%esp\n"   // Restore SP
+        "mov %2, %%eax\n"   // Put return address into A
+        "jmp *%%eax\n"      // Jump to A
+        :: "m"(env._bp), "m"(env._sp), "m"(env._pc)
+    );
+    // This point is unreachable :)
+}
+