Improved the BUILD_ASSERT macro to work outside of functions.

This will let us check the size of static array initializers.

Also moved this macro definition and ARRAY_SIZE into a new "tricks.h"
header, so that userspace utils can use it too.

BUG=none
BRANCH=none
TEST=manual

Built everything, tested on Link. Tried various assertions.

Change-Id: I612891108ea37dbca3572e0f25ab54a7bc0ed860
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/49417
Reviewed-by: Randall Spangler <rspangler@chromium.org>

7 files changed, 36 insertions, 25 deletions

diff --git a/chip/stm32/clock-stm32f100.c b/chip/stm32/clock-stm32f100.c
index ae919ca1b1..0dd63f456b 100644
--- a/chip/stm32/clock-stm32f100.c
+++ b/chip/stm32/clock-stm32f100.c
@@ -141,6 +141,7 @@ DECLARE_IRQ(STM32_IRQ_RTC_ALARM, __rtc_alarm_irq, 1);
 #else
 #error "Need board-specific clock settings"
 #endif
+BUILD_ASSERT(CPU_CLOCK == DESIRED_CPU_CLOCK);
 
 static void config_hispeed_clock(void)
 {
@@ -153,7 +154,6 @@ static void config_hispeed_clock(void)
 			;
 	}
 
-	BUILD_ASSERT(CPU_CLOCK == DESIRED_CPU_CLOCK);
 	STM32_RCC_CFGR = RCC_CFGR;
 	/* Enable the PLL */
 	STM32_RCC_CR |= 1 << 24;
diff --git a/chip/stm32/clock-stm32l15x.c b/chip/stm32/clock-stm32l15x.c
index 687919f73b..057888f68f 100644
--- a/chip/stm32/clock-stm32l15x.c
+++ b/chip/stm32/clock-stm32l15x.c
@@ -10,6 +10,8 @@
 #include "registers.h"
 #include "util.h"
 
+BUILD_ASSERT(CPU_CLOCK == 16000000);
+
 void enable_sleep(uint32_t mask)
 {
 	/* low power mode not implemented */
@@ -60,7 +62,6 @@ void clock_init(void)
 	 * stays on HSI, no prescaler, PLLSRC = HSI, PLLMUL = x3, PLLDIV = /3,
 	 * no MCO                      => PLLVCO = 48 MHz and PLLCLK = 16 Mhz
 	 */
-	BUILD_ASSERT(CPU_CLOCK == 16000000);
 	STM32_RCC_CFGR = 0x00800001;
 	/* Enable the PLL */
 	STM32_RCC_CR |= 1 << 24;
diff --git a/core/cortex-m/task.c b/core/cortex-m/task.c
index 47bbbee1e9..bd5736a3ae 100644
--- a/core/cortex-m/task.c
+++ b/core/cortex-m/task.c
@@ -109,6 +109,10 @@ static const struct {
 
 /* Contexts for all tasks */
 static task_ tasks[TASK_ID_COUNT];
+/* Sanity checks about static task invariants */
+BUILD_ASSERT(TASK_ID_COUNT <= sizeof(unsigned) * 8);
+BUILD_ASSERT(TASK_ID_COUNT < (1 << (sizeof(task_id_t) * 8)));
+
 
 /* Stacks for all tasks */
 #define TASK(n, r, d, s)  + s
@@ -613,10 +617,6 @@ void task_pre_init(void)
 	((task_ *)scratchpad)->stack = (uint32_t *)scratchpad;
 	*(uint32_t *)scratchpad = STACK_UNUSED_VALUE;
 
-	/* Sanity checks about static task invariants */
-	BUILD_ASSERT(TASK_ID_COUNT <= sizeof(unsigned) * 8);
-	BUILD_ASSERT(TASK_ID_COUNT < (1 << (sizeof(task_id_t) * 8)));
-
 	/* Initialize IRQs */
 	__nvic_init_irqs();
 }
diff --git a/include/compile_time_macros.h b/include/compile_time_macros.h
new file mode 100644
index 0000000000..9db583a7f2
--- /dev/null
+++ b/include/compile_time_macros.h
@@ -0,0 +1,26 @@
+/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* Handy clever tricks */
+
+#ifndef __CROS_EC_TRICKS_H
+#define __CROS_EC_TRICKS_H
+
+/* Test an important condition at compile time, not run time */
+#define _BA1_(cond, line) \
+	extern int __build_assertion_ ## line[1 - 2*!(cond)] \
+	__attribute__ ((unused))
+#define _BA0_(c, x) _BA1_(c, x)
+#define BUILD_ASSERT(cond) _BA0_(cond, __LINE__)
+
+/* Number of elements in an array */
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+
+/* Just in case - http://gcc.gnu.org/onlinedocs/gcc/Offsetof.html */
+#ifndef offsetof
+#define offsetof(type, member)  __builtin_offsetof(type, member)
+#endif
+
+#endif /* __CROS_EC_TRICKS_H */
diff --git a/include/util.h b/include/util.h
index c953e468f8..9db42c2f34 100644
--- a/include/util.h
+++ b/include/util.h
@@ -9,16 +9,11 @@
 #define __CROS_EC_UTIL_H
 
 #include "common.h"
+#include "compile_time_macros.h"
 #include "config.h"
 #include "panic.h"
 
 /**
- * Trigger a compilation failure if the condition
- * is not verified at build time.
- */
-#define BUILD_ASSERT(cond) ((void)sizeof(char[1 - 2*!(cond)]))
-
-/**
  * Trigger a debug exception if the condition
  * is not verified at runtime.
  */
@@ -41,12 +36,6 @@
 
 
 /* Standard macros / definitions */
-#ifndef ARRAY_SIZE
-#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
-#endif
-#ifndef OFFSET_OF
-#define OFFSET_OF(struc, field) ((uint32_t)&(((const struc * const)0)->field))
-#endif
 #ifndef MAX
 #define MAX(a, b) ((a) > (b) ? (a) : (b))
 #endif
diff --git a/util/ectool.c b/util/ectool.c
index b1115aefcd..0315b6dbb1 100644
--- a/util/ectool.c
+++ b/util/ectool.c
@@ -14,13 +14,11 @@
 
 #include "battery.h"
 #include "comm-host.h"
+#include "compile_time_macros.h"
 #include "ectool.h"
 #include "lightbar.h"
 #include "lock/gec_lock.h"
 
-/* Handy tricks */
-#define BUILD_ASSERT(cond) ((void)sizeof(char[1 - 2*!(cond)]))
-#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
 /* Don't use a macro where an inline will do... */
 static inline int MIN(int a, int b) { return a < b ? a : b; }
 
diff --git a/util/lbplay.c b/util/lbplay.c
index bcf90148e7..9cb853aa75 100644
--- a/util/lbplay.c
+++ b/util/lbplay.c
@@ -11,13 +11,10 @@
 #include <unistd.h>
 
 #include "comm-host.h"
+#include "compile_time_macros.h"
 #include "lightbar.h"
 #include "lock/gec_lock.h"
 
-/* Handy tricks */
-#define BUILD_ASSERT(cond) ((void)sizeof(char[1 - 2*!(cond)]))
-#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
-
 #define LB_SIZES(SUBCMD) { \
 		sizeof(((struct ec_params_lightbar *)0)->SUBCMD) \
 		+ sizeof(((struct ec_params_lightbar *)0)->cmd), \