Dynamic baseband module loading from SD card

firmware/application/m4_startup.cpp

@@ -22,12 +22,14 @@
 #include "m4_startup.hpp"
 
 #include "hal.h"
-
+#include "lpc43xx_cpp.hpp"
 #include "message.hpp"
 #include "portapack_shared_memory.hpp"
 
 #include <cstring>
 
+char * modhash;
+
 /* TODO: OK, this is cool, but how do I put the M4 to sleep so I can switch to
  * a different image? Other than asking the old image to sleep while the M0
  * makes changes?
@@ -37,6 +39,7 @@
  */
 void m4_init(const portapack::spi_flash::region_t from, const portapack::memory::region_t to) {
 	/* Initialize M4 code RAM */
+	// DEBUG
 	std::memcpy(reinterpret_cast<void*>(to.base()), from.base(), from.size);
 
 	/* M4 core is assumed to be sleeping with interrupts off, so we can mess
@@ -48,6 +51,58 @@ void m4_init(const portapack::spi_flash::region_t from, const portapack::memory:
 	LPC_RGU->RESET_CTRL[0] = (1 << 13);
 }
 
+int m4_load_image(void) {
+	uint32_t mod_size;
+	UINT bw;
+	uint8_t i;
+	char md5sum[16];
+	FILINFO modinfo;
+	FIL modfile;
+	DIR rootdir;
+	FRESULT res;
+	
+	// Scan SD card root directory for files with the right md5 fingerprint at the right location
+	f_opendir(&rootdir, "/");
+	for (;;) {
+		res = f_readdir(&rootdir, &modinfo);
+		if (res != FR_OK || modinfo.fname[0] == 0) break;
+		if (!(modinfo.fattrib & AM_DIR)) {
+			f_open(&modfile, modinfo.fname, FA_OPEN_EXISTING | FA_READ);
+			f_lseek(&modfile, 26);
+			f_read(&modfile, &md5sum, 16, &bw);
+			for (i = 0; i < 16; i++) {
+				if (md5sum[i] != modhash[i]) break;
+			}
+			if (i == 16) {
+				f_lseek(&modfile, 6);
+				f_read(&modfile, &mod_size, 4, &bw);
+				f_lseek(&modfile, 256);
+				f_read(&modfile, reinterpret_cast<void*>(portapack::memory::map::m4_code.base()), mod_size, &bw);
+				LPC_RGU->RESET_CTRL[0] = (1 << 13);
+				f_close(&modfile);
+				return 1;
+			}
+			f_close(&modfile);
+		}
+	}
+	
+	return 0;
+}
+
+void m4_switch(const char * hash) {
+	modhash = const_cast<char*>(hash);
+	
+	// Ask M4 to enter loop in RAM
+	BasebandConfiguration baseband_switch {
+		.mode = 0xFF,
+		.sampling_rate = 0,
+		.decimation_factor = 1,
+	};
+	
+	BasebandConfigurationMessage message { baseband_switch };
+	shared_memory.baseband_queue.push(message);
+}
+
 void m4_request_shutdown() {
 	ShutdownMessage shutdown_message;
 	shared_memory.baseband_queue.push(shutdown_message);