3 files changed, 65 insertions, 44 deletions

diff --git a/coroutine/arm32/Context.S b/coroutine/arm32/Context.S
new file mode 100644
index 0000000000..945e4f82d5
--- /dev/null
+++ b/coroutine/arm32/Context.S
@@ -0,0 +1,32 @@
+##
+##  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.
+##
+
+#define TOKEN_PASTE(x,y) x##y
+
+.file "Context.S"
+.text
+.globl PREFIXED_SYMBOL(coroutine_transfer)
+.align 2
+.type PREFIXED_SYMBOL(coroutine_transfer),%function
+.syntax unified
+
+PREFIXED_SYMBOL(coroutine_transfer):
+	# Save caller state (8 registers + return address)
+	push {r4-r11,lr}
+
+	# Save caller stack pointer
+	str sp, [r0]
+
+	# Restore callee stack pointer
+	ldr sp, [r1]
+
+	# Restore callee state (8 registers program counter)
+	pop {r4-r11,pc}
+
+#if defined(__linux__) && defined(__ELF__)
+.section .note.GNU-stack,"",%progbits
+#endif
diff --git a/coroutine/arm32/Context.h b/coroutine/arm32/Context.h
index 25f2bfcb3a..7529dd2efc 100644
--- a/coroutine/arm32/Context.h
+++ b/coroutine/arm32/Context.h
@@ -1,56 +1,59 @@
+#ifndef COROUTINE_ARM32_CONTEXT_H
+#define COROUTINE_ARM32_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. All rights reserved.
+ *  Copyright, 2018, by Samuel Williams.
 */
 
 #pragma once
 
 #include <assert.h>
+#include <stddef.h>
+#include <stdint.h>
 #include <string.h>
 
-#if __cplusplus
-extern "C" {
-#endif
-
-#define COROUTINE void
+#define COROUTINE __attribute__((noreturn)) void
+#define COROUTINE_LIMITED_ADDRESS_SPACE
 
-const size_t COROUTINE_REGISTERS = 9;
+enum {COROUTINE_REGISTERS = 8};
 
-typedef struct
+struct coroutine_context
 {
-	void **stack_pointer;
-} coroutine_context;
+    void **stack_pointer;
+    void *argument;
+};
 
-typedef void(* coroutine_start)(coroutine_context *from, coroutine_context *self);
+typedef COROUTINE(* coroutine_start)(struct coroutine_context *from, struct coroutine_context *self);
 
-inline void coroutine_initialize(
-	coroutine_context *context,
-	coroutine_start start,
-	void *stack_pointer,
-	size_t stack_size
+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
 ) {
-	context->stack_pointer = (void**)stack_pointer;
+    assert(start && stack && size >= 1024);
 
-	if (!start) {
-		assert(!context->stack_pointer);
-		/* We are main coroutine for this thread */
-		return;
-	}
+    // Stack grows down. Force 16-byte alignment.
+    char * top = (char*)stack + size;
+    context->stack_pointer = (void**)((uintptr_t)top & ~0xF);
 
-	*--context->stack_pointer = (void*)start;
+    *--context->stack_pointer = (void*)(uintptr_t)start;
 
-	context->stack_pointer -= COROUTINE_REGISTERS;
-	memset(context->stack_pointer, 0, sizeof(void*) * COROUTINE_REGISTERS);
+    context->stack_pointer -= COROUTINE_REGISTERS;
+    memset(context->stack_pointer, 0, sizeof(void*) * COROUTINE_REGISTERS);
 }
 
-coroutine_context * coroutine_transfer(coroutine_context * current, coroutine_context * target);
+struct coroutine_context * coroutine_transfer(struct coroutine_context * current, struct coroutine_context * target);
 
-inline void coroutine_destroy(coroutine_context * context)
+static inline void coroutine_destroy(struct coroutine_context * context)
 {
 }
 
-#if __cplusplus
-}
-#endif
+#endif /* COROUTINE_ARM32_CONTEXT_H */
diff --git a/coroutine/arm32/Context.s b/coroutine/arm32/Context.s
deleted file mode 100644
index 86a80f3db2..0000000000
--- a/coroutine/arm32/Context.s
+++ /dev/null
@@ -1,14 +0,0 @@
-##
-##  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. All rights reserved.
-##
-
-.text
-
-.globl coroutine_transfer
-coroutine_transfer:
-	stmia r1!, {r4-r11,sp,lr}
-	ldmia r0!, {r4-r11,sp,pc}
-	bx lr
\ No newline at end of file