2 files changed, 102 insertions, 0 deletions
diff --git a/coroutine/x86/Context.S b/coroutine/x86/Context.S
new file mode 100644
index 0000000000..b04e71aa1c
--- /dev/null
+++ b/coroutine/x86/Context.S
@@ -0,0 +1,41 @@
+##
+##  This file is part of the "Coroutine" project and released under the MIT License.
+##
+##  Created by Samuel Williams on 3/11/2018.
+##  Copyright, 2018, by Samuel Williams.
+##
+
+#define TOKEN_PASTE(x,y) x##y
+
+.text
+
+.globl PREFIXED_SYMBOL(coroutine_transfer)
+PREFIXED_SYMBOL(coroutine_transfer):
+
+	# Save caller registers
+	pushl %ebp
+	pushl %ebx
+	pushl %edi
+	pushl %esi
+
+	# Save caller stack pointer
+	movl %esp, (%ecx)
+
+	# Restore callee stack pointer
+	movl (%edx), %esp
+
+	# Restore callee stack
+	popl %esi
+	popl %edi
+	popl %ebx
+	popl %ebp
+
+	# Save the first argument as the return value
+	movl %ecx, %eax
+
+	# Jump to the address on the stack
+	ret
+
+#if (defined(__linux__) || defined(__FreeBSD__)) && defined(__ELF__)
+.section .note.GNU-stack,"",%progbits
+#endif
diff --git a/coroutine/x86/Context.h b/coroutine/x86/Context.h
new file mode 100644
index 0000000000..f33b338eab
--- /dev/null
+++ b/coroutine/x86/Context.h
@@ -0,0 +1,61 @@
+#ifndef COROUTINE_X86_CONTEXT_H
+#define COROUTINE_X86_CONTEXT_H 1
+
+/*
+ *  This file is part of the "Coroutine" project and released under the MIT License.
+ *
+ *  Created by Samuel Williams on 3/11/2018.
+ *  Copyright, 2018, by Samuel Williams.
+*/
+
+#pragma once
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#define COROUTINE __attribute__((noreturn, fastcall)) void
+#define COROUTINE_LIMITED_ADDRESS_SPACE
+
+enum {COROUTINE_REGISTERS = 4};
+
+struct coroutine_context
+{
+    void **stack_pointer;
+    void *argument;
+};
+
+typedef COROUTINE(* coroutine_start)(struct coroutine_context *from, struct coroutine_context *self) __attribute__((fastcall));
+
+static inline void coroutine_initialize_main(struct coroutine_context * context) {
+    context->stack_pointer = NULL;
+}
+
+static inline void coroutine_initialize(
+    struct coroutine_context *context,
+    coroutine_start start,
+    void *stack,
+    size_t size
+) {
+    assert(start && stack && size >= 1024);
+
+    // Stack grows down. Force 16-byte alignment.
+    char * top = (char*)stack + size;
+    context->stack_pointer = (void**)((uintptr_t)top & ~0xF);
+
+    *--context->stack_pointer = NULL;
+    *--context->stack_pointer = (void*)(uintptr_t)start;
+
+    context->stack_pointer -= COROUTINE_REGISTERS;
+    memset(context->stack_pointer, 0, sizeof(void*) * COROUTINE_REGISTERS);
+}
+
+struct coroutine_context * coroutine_transfer(struct coroutine_context * current, struct coroutine_context * target) __attribute__((fastcall));
+
+static inline void coroutine_destroy(struct coroutine_context * context)
+{
+    context->stack_pointer = NULL;
+}
+
+#endif /* COROUTINE_X86_CONTEXT_H */