pbdrv/stack: Move stack info to driver.

This lets us move it away from MicroPython's mphal so we can further unify all embedded ports.

Author: laurensvalk

bricks/_common/micropython.c

@@ -7,6 +7,8 @@
 #include <stdio.h>
 #include <string.h>
 
+#include <pbdrv/stack.h>
+
 #include <pbio/button.h>
 #include <pbio/main.h>
 #include <pbio/os.h>
@@ -350,7 +352,7 @@ void pbsys_main_run_program(pbsys_main_program_t *program) {
     // Note: stack control relies on main thread being initialised above
     char *sstack;
     char *estack;
-    pb_stack_get_info(&sstack, &estack);
+    pbdrv_stack_get_info(&sstack, &estack);
     #if PYBRICKS_OPT_USE_ESTACK
     mp_stack_set_top(estack);
     #else

bricks/_common/mphalport.h

@@ -8,7 +8,6 @@ void mp_hal_set_interrupt_char(int c);
 #define mp_hal_ticks_us pbdrv_clock_get_us
 #define mp_hal_ticks_cpu() 0
 #define mp_hal_delay_us pbdrv_clock_delay_us
-void pb_stack_get_info(char **sstack, char **estack);
 
 // Platform-specific code to run on completing the poll hook.
 void pb_event_poll_hook_leave(void);

bricks/_common/sources.mk

@@ -182,6 +182,7 @@ PBIO_SRC_C = $(addprefix lib/pbio/,\
 	drv/resistor_ladder/resistor_ladder.c \
 	drv/sound/sound_nxt.c \
 	drv/sound/sound_stm32_hal_dac.c \
+	drv/stack/stack_embedded.c \
 	drv/uart/uart_debug_first_port.c \
 	drv/uart/uart_ev3.c \
 	drv/uart/uart_ev3_pru.c \

bricks/_common_stm32/mphalport.c

@@ -17,13 +17,6 @@
 #include "py/mpconfig.h"
 #include "py/stream.h"
 
-void pb_stack_get_info(char **sstack, char **estack) {
-    extern uint32_t _estack;
-    extern uint32_t _sstack;
-    *sstack = (char *)&_sstack;
-    *estack = (char *)&_estack;
-}
-
 // using "internal" pbdrv variable
 extern volatile uint32_t pbdrv_clock_ticks;
 

bricks/ev3/mphalport.c

@@ -18,13 +18,6 @@
 #include "py/mpconfig.h"
 #include "py/stream.h"
 
-void pb_stack_get_info(char **sstack, char **estack) {
-    extern uint32_t _estack;
-    extern uint32_t _sstack;
-    *sstack = (char *)&_sstack;
-    *estack = (char *)&_estack;
-}
-
 // Core delay function that does an efficient sleep and may switch thread context.
 // If IRQs are enabled then we must have the GIL.
 void mp_hal_delay_ms(mp_uint_t Delay) {

bricks/nxt/mphalport.c

@@ -18,13 +18,6 @@
 #include "py/mpconfig.h"
 #include "py/stream.h"
 
-void pb_stack_get_info(char **sstack, char **estack) {
-    extern uint32_t __stack_start__;
-    extern uint32_t __stack_end__;
-    *sstack = (char *)&__stack_start__;
-    *estack = (char *)&__stack_end__;
-}
-
 // TODO
 static bool interrupts_get(void) {
     return true;

lib/pbio/drv/stack/stack_embedded.c

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2025 The Pybricks Authors
+
+#include <pbdrv/config.h>
+
+#if PBDRV_CONFIG_STACK_EMBEDDED
+
+#include <stdint.h>
+
+void pbdrv_stack_get_info(char **sstack, char **estack) {
+    // Defined in linker script.
+    extern uint32_t _estack;
+    extern uint32_t _sstack;
+    *sstack = (char *)&_sstack;
+    *estack = (char *)&_estack;
+}
+
+#endif // PBDRV_CONFIG_STACK_EMBEDDED

lib/pbio/include/pbdrv/stack.h

@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2025 The Pybricks Authors
+
+#ifndef _PBDRV_STACK_H_
+#define _PBDRV_STACK_H_
+
+#include <stddef.h>
+
+#include <pbdrv/config.h>
+
+#if PBDRV_CONFIG_STACK
+
+/**
+ * Gets the stack information.
+ *
+ * @param [out] sstack     The start of the stack.
+ * @param [out] estack     The end of the stack.
+ */
+void pbdrv_stack_get_info(char **sstack, char **estack);
+
+#else // PBDRV_CONFIG_STACK
+
+static inline void pbdrv_stack_get_info(char **sstack, char **estack) {
+    *sstack = NULL;
+    *estack = NULL;
+}
+
+#endif // PBDRV_CONFIG_STACK
+
+#endif // _PBDRV_STACK_H_

lib/pbio/platform/city_hub/pbdrvconfig.h

@@ -73,6 +73,9 @@
 #define PBDRV_CONFIG_UART_STM32F0                   (1)
 #define PBDRV_CONFIG_UART_STM32F0_NUM_UART          (2)
 
+#define PBDRV_CONFIG_STACK                          (1)
+#define PBDRV_CONFIG_STACK_EMBEDDED                 (1)
+
 #define PBDRV_CONFIG_WATCHDOG                       (1)
 #define PBDRV_CONFIG_WATCHDOG_STM32                 (1)
 

lib/pbio/platform/essential_hub/pbdrvconfig.h

@@ -103,6 +103,9 @@
 #define PBDRV_CONFIG_USB_PROD_STR                   LEGO_USB_PROD_STR_TECHNIC_SMALL_HUB " + Pybricks"
 #define PBDRV_CONFIG_USB_STM32F4                    (1)
 
+#define PBDRV_CONFIG_STACK                          (1)
+#define PBDRV_CONFIG_STACK_EMBEDDED                 (1)
+
 #define PBDRV_CONFIG_WATCHDOG                       (1)
 #define PBDRV_CONFIG_WATCHDOG_STM32                 (1)