From 365077772d3d8d5d479febd0388d7e74ef08d508 Mon Sep 17 00:00:00 2001
From: aliaspider
Date: Mon, 8 Dec 2014 22:56:33 +0100
Subject: start implementing the libretro interface. (not working yet)

---
 libco/sjlj.c | 115 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 115 insertions(+)
 create mode 100644 libco/sjlj.c

(limited to 'libco/sjlj.c')

diff --git a/libco/sjlj.c b/libco/sjlj.c
new file mode 100644
index 0000000..f074714
--- /dev/null
+++ b/libco/sjlj.c
@@ -0,0 +1,115 @@
+/*
+  libco.sjlj (2008-01-28)
+  author: Nach
+  license: public domain
+*/
+
+/*
+ * Note this was designed for UNIX systems. Based on ideas expressed in a paper
+ * by Ralf Engelschall.
+ * For SJLJ on other systems, one would want to rewrite springboard() and
+ * co_create() and hack the jmb_buf stack pointer.
+ */
+
+#define LIBCO_C
+#include <libco.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <setjmp.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct
+{
+   sigjmp_buf context;
+   void (*coentry)(void);
+   void *stack;
+} cothread_struct;
+
+static thread_local cothread_struct co_primary;
+static thread_local cothread_struct *creating, *co_running = 0;
+
+static void springboard(int ignored)
+{
+   if(sigsetjmp(creating->context, 0))
+      co_running->coentry();
+}
+
+cothread_t co_active(void)
+{
+  if (!co_running)
+     co_running = &co_primary;
+  return (cothread_t)co_running;
+}
+
+cothread_t co_create(unsigned int size, void (*coentry)(void))
+{
+   if(!co_running)
+      co_running = &co_primary;
+
+   cothread_struct *thread = (cothread_struct*)malloc(sizeof(cothread_struct));
+
+   if(thread)
+   {
+      struct sigaction handler;
+      struct sigaction old_handler;
+
+      stack_t stack;
+      stack_t old_stack;
+
+      thread->coentry = thread->stack = 0;
+
+      stack.ss_flags = 0;
+      stack.ss_size = size;
+      thread->stack = stack.ss_sp = malloc(size);
+
+      if(stack.ss_sp && !sigaltstack(&stack, &old_stack))
+      {
+         handler.sa_handler = springboard;
+         handler.sa_flags = SA_ONSTACK;
+         sigemptyset(&handler.sa_mask);
+         creating = thread;
+
+         if(!sigaction(SIGUSR1, &handler, &old_handler))
+         {
+            if(!raise(SIGUSR1))
+               thread->coentry = coentry;
+            sigaltstack(&old_stack, 0);
+            sigaction(SIGUSR1, &old_handler, 0);
+         }
+      }
+
+      if(thread->coentry != coentry)
+      {
+         co_delete(thread);
+         thread = 0;
+      }
+   }
+
+   return (cothread_t)thread;
+}
+
+void co_delete(cothread_t cothread)
+{
+   if(cothread)
+   {
+      if(((cothread_struct*)cothread)->stack)
+         free(((cothread_struct*)cothread)->stack);
+      free(cothread);
+   }
+}
+
+void co_switch(cothread_t cothread)
+{
+   if(!sigsetjmp(co_running->context, 0))
+   {
+      co_running = (cothread_struct*)cothread;
+      siglongjmp(co_running->context, 1);
+   }
+}
+
+#ifdef __cplusplus
+}
+#endif
-- 
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