3 files changed, 168 insertions, 0 deletions
diff --git a/coroutine/win32/Context.S b/coroutine/win32/Context.S
new file mode 100644
index 0000000000..d14bf435e8
--- /dev/null
+++ b/coroutine/win32/Context.S
@@ -0,0 +1,47 @@
+##
+##  This file is part of the "Coroutine" project and released under the MIT License.
+##
+##  Created by Lars Kanis on 06/06/2019.
+##
+
+.text
+
+# Using fastcall is a big win (and it's the same as how x64 works).
+# In coroutine transfer, the arguments are passed in ecx and edx. We don't need
+# to touch these in order to pass them to the destination coroutine.
+
+.globl @coroutine_transfer@8
+@coroutine_transfer@8:
+	# Save the thread information block:
+	pushl %fs:0
+	pushl %fs:4
+	pushl %fs:8
+
+	# 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
+
+	# Restore the thread information block:
+	popl %fs:8
+	popl %fs:4
+	popl %fs:0
+
+	# Save the first argument as the return value:
+	movl %ecx, %eax
+
+	# Jump to the address on the stack:
+	ret
diff --git a/coroutine/win32/Context.asm b/coroutine/win32/Context.asm
new file mode 100644
index 0000000000..f8f431239b
--- /dev/null
+++ b/coroutine/win32/Context.asm
@@ -0,0 +1,55 @@
+;;
+;;  This file is part of the "Coroutine" project and released under the MIT License.
+;;
+;;  Created by Samuel Williams on 10/5/2018.
+;;  Copyright, 2018, by Samuel Williams.
+;;
+
+.386
+.model flat
+
+.code
+
+assume fs:nothing
+
+; Using fastcall is a big win (and it's the same has how x64 works).
+; In coroutine transfer, the arguments are passed in ecx and edx. We don't need
+; to touch these in order to pass them to the destination coroutine.
+
+@coroutine_transfer@8 proc
+	; Save the thread information block:
+	push fs:[0]
+	push fs:[4]
+	push fs:[8]
+
+	; Save caller registers:
+	push ebp
+	push ebx
+	push edi
+	push esi
+
+	; Save caller stack pointer:
+	mov dword ptr [ecx], esp
+
+	; Restore callee stack pointer:
+	mov esp, dword ptr [edx]
+
+	; Restore callee stack:
+	pop esi
+	pop edi
+	pop ebx
+	pop ebp
+
+	; Restore the thread information block:
+	pop fs:[8]
+	pop fs:[4]
+	pop fs:[0]
+
+	; Save the first argument as the return value:
+	mov eax, dword ptr ecx
+
+	; Jump to the address on the stack:
+	ret
+@coroutine_transfer@8 endp
+
+end
diff --git a/coroutine/win32/Context.h b/coroutine/win32/Context.h
new file mode 100644
index 0000000000..c1c8fbcd13
--- /dev/null
+++ b/coroutine/win32/Context.h
@@ -0,0 +1,66 @@
+#ifndef COROUTINE_WIN32_CONTEXT_H
+#define COROUTINE_WIN32_CONTEXT_H 1
+
+/*
+ *  This file is part of the "Coroutine" project and released under the MIT License.
+ *
+ *  Created by Samuel Williams on 10/5/2018.
+ *  Copyright, 2018, by Samuel Williams.
+*/
+
+#pragma once
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#define COROUTINE __declspec(noreturn) void __fastcall
+#define COROUTINE_DECL void __fastcall
+#define COROUTINE_LIMITED_ADDRESS_SPACE
+
+/* This doesn't include thread information block */
+enum {COROUTINE_REGISTERS = 4};
+
+struct coroutine_context
+{
+    void **stack_pointer;
+    void *argument;
+};
+
+typedef void(__fastcall * coroutine_start)(struct coroutine_context *from, struct coroutine_context *self);
+
+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 = (void*)(uintptr_t)start;
+
+    /* Windows Thread Information Block */
+    *--context->stack_pointer = (void*)0xFFFFFFFF; /* fs:[0] */
+    *--context->stack_pointer = (void*)top; /* fs:[4] */
+    *--context->stack_pointer = (void*)stack;  /* fs:[8] */
+
+    context->stack_pointer -= COROUTINE_REGISTERS;
+    memset(context->stack_pointer, 0, sizeof(void*) * COROUTINE_REGISTERS);
+}
+
+struct coroutine_context * __fastcall coroutine_transfer(struct coroutine_context * current, struct coroutine_context * target);
+
+static inline void coroutine_destroy(struct coroutine_context * context)
+{
+}
+
+#endif /* COROUTINE_WIN32_CONTEXT_H */