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Marlin/src/HAL/DUE/InterruptVectors.cpp

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+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+
+/**
+ * InterruptVectors_Due.cpp - This module relocates the Interrupt vector table to SRAM,
+ *  allowing to register new interrupt handlers at runtime. Specially valuable and needed
+ * because Arduino runtime allocates some interrupt handlers that we NEED to override to
+ * properly support extended functionality, as for example, USB host or USB device (MSD, MTP)
+ * and custom serial port handlers, and we don't actually want to modify and/or recompile the
+ * Arduino runtime. We just want to run as much as possible on Stock Arduino
+ *
+ * Copyright (c) 2017 Eduardo José Tagle. All right reserved
+ */
+#ifdef ARDUINO_ARCH_SAM
+
+#include "../../inc/MarlinConfig.h"
+#include "HAL.h"
+#include "InterruptVectors.h"
+
+/* The relocated Exception/Interrupt Table - According to the ARM
+   reference manual, alignment to 128 bytes should suffice, but in
+   practice, we need alignment to 256 bytes to make this work in all
+   cases */
+__attribute__ ((aligned(256)))
+static DeviceVectors ram_tab = { nullptr };
+
+/**
+ * This function checks if the exception/interrupt table is already in SRAM or not.
+ * If it is not, then it copies the ROM table to the SRAM and relocates the table
+ * by reprogramming the NVIC registers
+ */
+static pfnISR_Handler* get_relocated_table_addr() {
+  // Get the address of the interrupt/exception table
+  uint32_t isrtab = SCB->VTOR;
+
+  // If already relocated, we are done!
+  if (isrtab >= IRAM0_ADDR)
+    return (pfnISR_Handler*)isrtab;
+
+  // Get the address of the table stored in FLASH
+  const pfnISR_Handler* romtab = (const pfnISR_Handler*)isrtab;
+
+  // Copy it to SRAM
+  memcpy(&ram_tab, romtab, sizeof(ram_tab));
+
+  // Disable global interrupts
+  CRITICAL_SECTION_START();
+
+  // Set the vector table base address to the SRAM copy
+  SCB->VTOR = (uint32_t)(&ram_tab);
+
+  // Reenable interrupts
+  CRITICAL_SECTION_END();
+
+  // Return the address of the table
+  return (pfnISR_Handler*)(&ram_tab);
+}
+
+pfnISR_Handler install_isr(IRQn_Type irq, pfnISR_Handler newHandler) {
+  // Get the address of the relocated table
+  pfnISR_Handler *isrtab = get_relocated_table_addr();
+
+  // Disable global interrupts
+  CRITICAL_SECTION_START();
+
+  // Get the original handler
+  pfnISR_Handler oldHandler = isrtab[irq + 16];
+
+  // Install the new one
+  isrtab[irq + 16] = newHandler;
+
+  // Reenable interrupts
+  CRITICAL_SECTION_END();
+
+  // Return the original one
+  return oldHandler;
+}
+
+#endif