Add PICO_FLASH_BANK_FIXED_OFFSET

Defaults to true. Can be set to false if the flash bank offset is
dynamically generated, e.g. to be inside the binary itself.

Fixes #1278

src/rp2_common/pico_btstack/btstack_flash_bank.c

@@ -9,10 +9,12 @@
 #include "hardware/sync.h"
 #include <string.h>
 
+#if PICO_FLASH_BANK_FIXED_OFFSET
 // Check sizes
 static_assert(PICO_FLASH_BANK_TOTAL_SIZE % (FLASH_SECTOR_SIZE * 2) == 0, "PICO_FLASH_BANK_TOTAL_SIZE invalid");
 static_assert(PICO_FLASH_BANK_TOTAL_SIZE <= PICO_FLASH_SIZE_BYTES, "PICO_FLASH_BANK_TOTAL_SIZE too big");
 static_assert(PICO_FLASH_BANK_STORAGE_OFFSET + PICO_FLASH_BANK_TOTAL_SIZE <= PICO_FLASH_SIZE_BYTES, "PICO_FLASH_BANK_TOTAL_SIZE too big");
+#endif
 
 // Size of one bank
 #define PICO_FLASH_BANK_SIZE (PICO_FLASH_BANK_TOTAL_SIZE / 2)
@@ -133,8 +135,7 @@ static const hal_flash_bank_t pico_flash_bank_instance_obj = {
 };
 
 const hal_flash_bank_t *pico_flash_bank_instance(void) {
-
-#ifndef NDEBUG
+#if !defined NDEBUG && PICO_FLASH_BANK_FIXED_OFFSET
     // Check we're not overlapping the binary in flash
     extern char __flash_binary_end;
     assert((uintptr_t)&__flash_binary_end - XIP_BASE <= PICO_FLASH_BANK_STORAGE_OFFSET);

src/rp2_common/pico_btstack/include/pico/btstack_flash_bank.h

@@ -24,6 +24,11 @@ extern "C" {
 #define PICO_FLASH_BANK_STORAGE_OFFSET (PICO_FLASH_SIZE_BYTES - PICO_FLASH_BANK_TOTAL_SIZE)
 #endif
 
+// PICO_CONFIG: PICO_FLASH_BANK_FIXED_OFFSET, Indicates if the flash bank is at a fixed address, or else it's dynamically generated e.g. to be inside the binary itself, type=bool, default=1, group=pico_btstack
+#ifndef PICO_FLASH_BANK_FIXED_OFFSET
+#define PICO_FLASH_BANK_FIXED_OFFSET 1
+#endif
+
 /**
  * \brief Return the singleton BTstack HAL flash instance, used for non-volatile storage
  * \ingroup pico_btstack