atom: reimplement in pure assembly

arch/at91sam3x8e/CMakeLists.txt

@@ -7,6 +7,7 @@ target_compile_options(ardix_arch PRIVATE ${ARDIX_COMPILE_OPTIONS})
 target_include_directories(ardix_arch PRIVATE ${ARDIX_INCLUDE_DIRS})
 
 target_sources(ardix_arch PRIVATE
+	atom_get_put.S
 	atom.c
 	atomic.c
 	entry.c

arch/at91sam3x8e/atom.c

@@ -1,52 +1,13 @@
 /* See the end of this file for copyright, license, and warranty information. */
 
 #include <ardix/atom.h>
+#include <stddef.h>
 
 void atom_init(atom_t *atom)
 {
 	atom->count = 0;
 }
 
-int atom_get(atom_t *atom)
-{
-	int tmp;
-	int newval;
-	atom_t atom_val;
-
-	__asm__ volatile(
-"1:	ldrex	%0,	[%3]		\n"	/* atom_val = *atom */
-"	add	%1,	%0,	#1	\n"	/* newval = atom_val.count + 1 */
-"	strex	%2,	%1,	[%3]	\n"	/* *atom = newval */
-"	teq	%2,	#0		\n"	/* store successful? */
-"	bne	1b			\n"	/*  -> goto 1 if not */
-"	dmb				"	/* memory barrier */
-	: "=&r" (atom_val), "=&r" (newval), "=&r" (tmp)
-	: "r" (atom)
-	: "cc");
-
-	return newval;
-}
-
-int atom_put(atom_t *atom)
-{
-	int tmp;
-	int newval;
-	atom_t atom_val;
-
-	__asm__ volatile(
-"1:	ldrex	%0,	[%3]		\n"	/* atom_val = *atom */
-"	sub	%1,	%0,	#1	\n"	/* newval = atom_val.count - 1 */
-"	strex	%2,	%1,	[%3]	\n"	/* *atom = newval */
-"	teq	%2,	#0		\n"	/* store successful? */
-"	bne	1b			\n"	/*   -> goto 1 if not */
-"	dmb				"	/* memory barrier */
-	: "=&r" (atom_val), "=&r" (newval), "=&r" (tmp)
-	: "r" (atom)
-	: "cc");
-
-	return newval;
-}
-
 int atom_count(atom_t *atom)
 {
 	return atom->count;

arch/at91sam3x8e/atom_get_put.S

@@ -0,0 +1,46 @@
+/* See the end of this file for copyright, license, and warranty information. */
+
+.include "asm.S"
+
+.text
+
+/* int _atom_get(int *count); */
+func_begin _atom_get
+
+	ldrex	r1,	[r0]		/* int tmp = atom->count */
+	add	r2,	r1,	#1	/* int newval = tmp + 1 */
+	strex	r3,	r2,	[r0]	/* atom->count = newval */
+	teq	r3,	#0		/* store successful? */
+	bne	_atom_get		/*   -> goto _atom_get to try again if not */
+	dmb				/* data memory barrier */
+	mov	r0,	r2		/* return newval */
+	bx	lr
+
+func_end _atom_get
+
+/* int _atom_put(int *count); */
+func_begin _atom_put
+
+	ldrex	r1,	[r0]		/* int tmp = atom->count */
+	sub	r2,	r1,	#1	/* int newval = tmp - 1 */
+	strex	r3,	r2,	[r0]	/* atom->count = newval */
+	teq	r3,	#0		/* store successful? */
+	bne	_atom_put		/*   -> goto _atom_put to try again if not */
+	dmb				/* data memory barrier */
+	mov	r0,	r2		/* return newval */
+	bx	lr
+
+func_end _atom_put
+
+/*
+ * This file is part of Ardix.
+ * Copyright (c) 2021 Felix Kopp <owo@fef.moe>.
+ *
+ * Ardix is non-violent software: you may only use, redistribute,
+ * and/or modify it under the terms of the CNPLv6+ as found in
+ * the LICENSE file in the source code root directory or at
+ * <https://git.pixie.town/thufie/CNPL>.
+ *
+ * Ardix comes with ABSOLUTELY NO WARRANTY, to the extent
+ * permitted by applicable law.  See the CNPLv6+ for details.
+ */

arch/at91sam3x8e/include/asm.S

@@ -0,0 +1,28 @@
+/* See the end of this file for copyright, license, and warranty information. */
+
+.syntax unified
+.thumb
+.cpu cortex-m3
+
+.macro func_begin name
+	.global \name
+	.type \name, "function"
+\name :
+.endm
+
+.macro func_end name
+	.size \name, .-\name
+.endm
+
+/*
+ * This file is part of Ardix.
+ * Copyright (c) 2021 Felix Kopp <owo@fef.moe>.
+ *
+ * Ardix is non-violent software: you may only use, redistribute,
+ * and/or modify it under the terms of the CNPLv6+ as found in
+ * the LICENSE file in the source code root directory or at
+ * <https://git.pixie.town/thufie/CNPL>.
+ *
+ * Ardix comes with ABSOLUTELY NO WARRANTY, to the extent
+ * permitted by applicable law.  See the CNPLv6+ for details.
+ */

arch/at91sam3x8e/toolchain.cmake

@@ -16,8 +16,10 @@ set(CMAKE_RANLIB	${TOOLCHAIN_PATH}/arm-none-eabi-ranlib${CMAKE_EXECUTABLE_SUFFIX
 set(CMAKE_SZE		${TOOLCHAIN_PATH}/arm-none-eabi-size${CMAKE_EXECUTABLE_SUFFIX} CACHE INTERNAL "")
 set(CMAKE_STRIP		${TOOLCHAIN_PATH}/arm-none-eabi-strip${CMAKE_EXECUTABLE_SUFFIX} CACHE INTERNAL "")
 
-set(CMAKE_C_FLAGS "-Os -nodefaultlibs -nostartfiles -mcpu=cortex-m3 -mthumb -mabi=aapcs -march=armv7-m -masm-syntax-unified")
-set(CMAKE_C_FLAGS_DEBUG -g)
+set(CMAKE_C_FLAGS "-Os -nodefaultlibs -nostartfiles -mcpu=cortex-m3 -mabi=aapcs")
+if(DEBUG)
+	set(CMAKE_C_FLAGS "-g ${CMAKE_C_FLAGS}")
+endif()
 
 set(CMAKE_LINKER_FLAGS "-T${CMAKE_CURRENT_LIST_DIR}/config.ld -T${CMAKE_CURRENT_LIST_DIR}/flash.ld --whole-archive")
 set(ARDIX_LINKER_FLAGS

include/ardix/atom.h

@@ -3,14 +3,24 @@
 #pragma once
 
 #include <ardix/types.h>
+#include <toolchain.h>
 
 #define ATOM_DEFINE(name) atom_t name = { .count = 0, }
 
 void atom_init(atom_t *atom);
 
-int atom_get(atom_t *atom);
+extern int _atom_get(int *count);
+extern int _atom_put(int *count);
 
-int atom_put(atom_t *atom);
+__always_inline int atom_get(atom_t *atom)
+{
+	return _atom_get(&atom->count);
+}
+
+__always_inline int atom_put(atom_t *atom)
+{
+	return _atom_get(&atom->count);
+}
 
 int atom_count(atom_t *atom);