8kSps rate; elf in SRAM2

Makefile

@@ -5,7 +5,7 @@
 
 # Compiler options here.
 ifeq ($(USE_OPT),)
-  USE_OPT = -Og -ggdb -fomit-frame-pointer -falign-functions=16
+  USE_OPT = -Og -ggdb -fomit-frame-pointer -falign-functions=16 -mtune=cortex-m4
 endif
 
 # C specific options here (added to USE_OPT).
@@ -15,7 +15,7 @@ endif
 
 # C++ specific options here (added to USE_OPT).
 ifeq ($(USE_CPPOPT),)
-  USE_CPPOPT = -std=c++2a -fno-rtti -fno-exceptions
+  USE_CPPOPT = -std=c++2a -fno-rtti -fno-exceptions 
 endif
 
 # Enable this if you want the linker to remove unused code and data.

gui/wxmain.cpp

@@ -176,16 +176,24 @@ void MainFrame::prepareEditor()
         wxT("void char short int long auto float double unsigned signed "
             "volatile static const constexpr constinit consteval "
             "virtual final noexcept public private protected"));
-    m_text_editor->SetText("void process_data(adcsample_t *samples, unsigned int size)\n{\n\t\n}\n");
+    m_text_editor->SetText(
+R"cpp(adcsample_t *process_data(adcsample_t *samples, unsigned int size)
+{
+    return samples;
+}
+)cpp");
 }
 
 static const char *makefile_text = R"make(
 all:
-	@arm-none-eabi-g++ -x c++ -mcpu=cortex-m4 -mthumb -mfloat-abi=hard -mfpu=fpv4-sp-d16 -Os --specs=nosys.specs -nostartfiles -fPIE $0 -o $0.o -Wl,-Ttext-segment=0 -Wl,-eprocess_data_entry -Wl,-zmax-page-size=512
+	@arm-none-eabi-g++ -x c++ -Os -fno-exceptions -fno-rtti \
+	                   -mcpu=cortex-m4 -mthumb -mfloat-abi=hard -mfpu=fpv4-sp-d16 -mtune=cortex-m4 \
+	                   -nostartfiles \
+	                   -Wl,-Ttext-segment=0x10000000 -Wl,-zmax-page-size=512 -Wl,-eprocess_data_entry \
+	                   $0 -o $0.o
 	@cp $0.o $0.orig.o
 	@arm-none-eabi-strip -s -S --strip-unneeded $0.o
-	@arm-none-eabi-objcopy --remove-section .ARM.exidx \
-                           --remove-section .ARM.attributes \
+	@arm-none-eabi-objcopy --remove-section .ARM.attributes \
                            --remove-section .comment \
                            --remove-section .noinit \
                            $0.o
@@ -196,14 +204,15 @@ static const char *file_header = R"cpp(
 
 using adcsample_t = uint16_t;
 
-void process_data(adcsample_t *samples, unsigned int size);
+adcsample_t *process_data(adcsample_t *samples, unsigned int size);
 
-extern "C" void process_data_entry() {
-    auto func = (void (*)())process_data;
-    func();
+extern "C" void process_data_entry()
+{
+    ((void (*)())process_data)();
 }
 
 // End stmdspgui header code
+
 )cpp";
 
 wxString MainFrame::compileEditorCode()

openocd.sh

@@ -0,0 +1 @@
+sudo openocd -f /usr/local/share/openocd/scripts/interface/stlink.cfg -f /usr/local/share/openocd/scripts/target/stm32l4x.cfg

source/adc.cpp

@@ -29,7 +29,7 @@ static ADCConversionGroup adc_group_config = {
     .cfgr2 = 0,
     .tr1 = ADC_TR(0, 4095),
     .smpr = {
-        ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_24P5), 0
+        ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_2P5), 0
     },
     .sqr = {
         ADC_SQR1_SQ1_N(ADC_CHANNEL_IN5),
@@ -38,7 +38,7 @@ static ADCConversionGroup adc_group_config = {
 };
 
 constexpr static const GPTConfig gpt_config = {
-    .frequency = 4000000,
+    .frequency = 600000,
     .callback = nullptr,
     .cr2 = TIM_CR2_MMS_1, /* TRGO */
     .dier = 0
@@ -65,7 +65,7 @@ namespace adc
         adc_is_read_finished = false;
         adc_group_config.circular = false;
         adcStartConversion(adcd, &adc_group_config, buffer, count);
-        gptStartContinuous(gptd, 8);
+        gptStartContinuous(gptd, 5);
         while (!adc_is_read_finished);
         return buffer;
     }
@@ -77,7 +77,7 @@ namespace adc
         adc_operation_func = operation_func;
         adc_group_config.circular = true;
         adcStartConversion(adcd, &adc_group_config, buffer, count);
-        gptStartContinuous(gptd, 8);
+        gptStartContinuous(gptd, 5);
     }
     
     void read_stop()

source/dac.cpp

@@ -28,7 +28,7 @@ constexpr static const DACConversionGroup dac_group_config = {
 };
 
 constexpr static const GPTConfig gpt_config = {
-  .frequency = 4000000,
+  .frequency = 600000,
   .callback = nullptr,
   .cr2 = TIM_CR2_MMS_1, /* TRGO */
   .dier = 0
@@ -48,7 +48,7 @@ namespace dac
     void write_start(dacsample_t *buffer, size_t count)
     {
         dacStartConversion(dacd, &dac_group_config, buffer, count);
-        gptStartContinuous(gptd, 8);
+        gptStartContinuous(gptd, 5);
     }
     
     void write_stop()

source/elf_load.cpp

@@ -4,6 +4,8 @@
 #include <algorithm>
 #include <cstring>
 
+//constexpr unsigned int ELF_LOAD_ADDR = 0x10000000;
+
 static const unsigned char elf_header[] = { '\177', 'E', 'L', 'F' };
 
 template<typename T>
@@ -12,67 +14,58 @@ constexpr static auto ptr_from_offset(void *base, uint32_t offset)
     return reinterpret_cast<T>(reinterpret_cast<uint8_t *>(base) + offset);
 }
 
-static Elf32_Shdr *find_section(Elf32_Ehdr *ehdr, const char *name);
+//static Elf32_Shdr *find_section(Elf32_Ehdr *ehdr, const char *name);
 
 namespace elf {
 
-entry_t load(void *elf_data, void *elf_load_offset)
+entry_t load(void *elf_data)
 {
+    // Check the ELF's header signature
     auto ehdr = reinterpret_cast<Elf32_Ehdr *>(elf_data);
     if (!std::equal(ehdr->e_ident, ehdr->e_ident + 4, elf_header))
         return nullptr;
 
+    // Iterate through program header LOAD sections
+    bool loaded = false;
     auto phdr = ptr_from_offset<Elf32_Phdr *>(elf_data, ehdr->e_phoff);
     for (Elf32_Half i = 0; i < ehdr->e_phnum; i++) {
         if (phdr->p_type == PT_LOAD) {
-            std::memcpy(ptr_from_offset<void *>(elf_load_offset, phdr->p_vaddr),
-                        ptr_from_offset<void *>(elf_data, phdr->p_offset),
-                        phdr->p_filesz);
-            //break;
+            if (phdr->p_filesz == 0) {
+                std::memset(reinterpret_cast<void *>(phdr->p_vaddr),
+                            0,
+                            phdr->p_memsz);
+            } else {
+                std::memcpy(reinterpret_cast<void *>(phdr->p_vaddr),
+                            ptr_from_offset<void *>(elf_data, phdr->p_offset),
+                            phdr->p_filesz);
+                if (!loaded)
+                    loaded = true;
+            }
         }
 
         phdr = ptr_from_offset<Elf32_Phdr *>(phdr, ehdr->e_phentsize);
     }
 
-    // Zero .bss section
-    if (auto bss_section = find_section(ehdr, ".bss"); bss_section) {
-        auto bss = ptr_from_offset<uint32_t *>(elf_load_offset, bss_section->sh_addr);
-        std::fill(bss, bss + bss_section->sh_size / sizeof(uint32_t), 0);
-    }
-
-    // Fix global offset table (GOT) entries
-    if (auto got_section = find_section(ehdr, ".got"); got_section) {
-        auto got = ptr_from_offset<void **>(elf_load_offset, got_section->sh_addr);
-        for (size_t i = 0; i < got_section->sh_size / sizeof(void *); i++)
-            got[i] = ptr_from_offset<void *>(got[i], reinterpret_cast<uint32_t>(elf_load_offset));
-    }
-
-    //// Run any initial constructors
-    //if (auto init_section = find_section(ehdr, ".init_array"); init_section) {
-    //    auto init_array = reinterpret_cast<void (**)()>(elf_load_offset + init_section->sh_addr);
-    //    std::for_each(init_array, init_array + init_section->sh_size / sizeof(void (*)()),
-    //                  [elf_load_offset](auto func) { (func + elf_load_offset)(); });
-    //}
 
-    return ptr_from_offset<entry_t>(elf_load_offset, ehdr->e_entry);
+    return loaded ? reinterpret_cast<entry_t>(ehdr->e_entry) : nullptr;
 }
 
 } // namespace elf
 
-Elf32_Shdr *find_section(Elf32_Ehdr *ehdr, const char *name)
-{
-    auto shdr = ptr_from_offset<Elf32_Shdr *>(ehdr, ehdr->e_shoff);
-    auto shdr_str = ptr_from_offset<Elf32_Shdr *>(ehdr,
-        ehdr->e_shoff + ehdr->e_shstrndx * ehdr->e_shentsize);
-
-    for (Elf32_Half i = 0; i < ehdr->e_shnum; i++) {
-        char *section = ptr_from_offset<char *>(ehdr, shdr_str->sh_offset) + shdr->sh_name;
-        if (!strcmp(section, name))
-            return shdr;
-
-        shdr = ptr_from_offset<Elf32_Shdr *>(shdr, ehdr->e_shentsize);
-    }
-
-    return 0;
-}
+//Elf32_Shdr *find_section(Elf32_Ehdr *ehdr, const char *name)
+//{
+//    auto shdr = ptr_from_offset<Elf32_Shdr *>(ehdr, ehdr->e_shoff);
+//    auto shdr_str = ptr_from_offset<Elf32_Shdr *>(ehdr,
+//        ehdr->e_shoff + ehdr->e_shstrndx * ehdr->e_shentsize);
+//
+//    for (Elf32_Half i = 0; i < ehdr->e_shnum; i++) {
+//        char *section = ptr_from_offset<char *>(ehdr, shdr_str->sh_offset) + shdr->sh_name;
+//        if (!strcmp(section, name))
+//            return shdr;
+//
+//        shdr = ptr_from_offset<Elf32_Shdr *>(shdr, ehdr->e_shentsize);
+//    }
+//
+//    return 0;
+//}
 

source/elf_load.hpp

@@ -6,9 +6,9 @@
 
 namespace elf
 {
-    using entry_t = void (*)(uint16_t *, size_t);
+    using entry_t = uint16_t *(*)(uint16_t *, size_t);
 
-    entry_t load(void *elf_data, void *elf_load_offset);
+    entry_t load(void *elf_data);
 }
 
 #endif // ELF_LOAD_HPP_

source/main.cpp

@@ -19,6 +19,8 @@
 
 #include <array>
 
+constexpr unsigned int MAX_SAMPLE_BUFFER_SIZE = 2048;
+
 enum class RunStatus : char
 {
     Idle = '1',
@@ -42,14 +44,13 @@ static_assert(sizeof(dacsample_t) == sizeof(uint16_t));
 #if CACHE_LINE_SIZE > 0
 CC_ALIGN(CACHE_LINE_SIZE)
 #endif
-static std::array<adcsample_t, CACHE_SIZE_ALIGN(adcsample_t, 2048)> adc_samples;
+static std::array<adcsample_t, CACHE_SIZE_ALIGN(adcsample_t, MAX_SAMPLE_BUFFER_SIZE)> adc_samples;
 #if CACHE_LINE_SIZE > 0
 CC_ALIGN(CACHE_LINE_SIZE)
 #endif
-static std::array<dacsample_t, CACHE_SIZE_ALIGN(dacsample_t, 2048)> dac_samples;
+static std::array<dacsample_t, CACHE_SIZE_ALIGN(dacsample_t, MAX_SAMPLE_BUFFER_SIZE)> dac_samples;
 
-static uint8_t elf_file_store[2048];
-static uint8_t elf_exec_store[4096];
+static uint8_t elf_file_store[8192];
 static elf::entry_t elf_entry = nullptr;
 
 static void signal_operate(adcsample_t *buffer, size_t count);
@@ -57,81 +58,125 @@ static void main_loop();
 
 int main()
 {
+    // Initialize the RTOS
     halInit();
     chSysInit();
 
     // Enable FPU
     SCB->CPACR |= 0xF << 20;
 
-    palSetPadMode(GPIOA, 5,  PAL_MODE_OUTPUT_PUSHPULL); // LED
+    // Prepare LED
+    palSetPadMode(GPIOA, 5,  PAL_MODE_OUTPUT_PUSHPULL);
+    palClearPad(GPIOA, 5);
 
     adc::init();
     dac::init();
     usbserial::init();
 
+    // Start the conversion manager thread
     chThdCreateStatic(conversionThreadWA, sizeof(conversionThreadWA),
                       NORMALPRIO,
                       conversionThread, nullptr);
+
     main_loop();
 }
 
 void main_loop()
 {
-    static unsigned int dac_sample_count = 2048;
-	while (true) {
+    static unsigned int dac_sample_count = MAX_SAMPLE_BUFFER_SIZE;
+
+	while (1) {
         if (usbserial::is_active()) {
-            // Expect to receive a byte command 'packet'.
+            // Attempt to receive a command packet
             if (char cmd[3]; usbserial::read(&cmd, 1) > 0) {
+                // Packet received, first byte represents the desired command/action
                 switch (cmd[0]) {
-                case 'r': // Read in analog signal
-                    if (usbserial::read(&cmd[1], 2) < 2)
+
+                // 'r' - Conduct a single sample of the ADC, and send the results back over USB.
+                case 'r':
+                    // Get the next two bytes of the packet to determine the desired sample size
+                    if (run_status != RunStatus::Idle || usbserial::read(&cmd[1], 2) < 2)
                         break;
-                    if (auto count = std::min(static_cast<unsigned int>(cmd[1] | (cmd[2] << 8)), adc_samples.size()); count > 0) {
-                        adc::read(&adc_samples[0], count);
-                        usbserial::write(adc_samples.data(), count * sizeof(adcsample_t));
+                    if (unsigned int desiredSize = cmd[1] | (cmd[2] << 8); desiredSize <= adc_samples.size()) {
+                        adc::read(&adc_samples[0], desiredSize);
+                        usbserial::write(adc_samples.data(), desiredSize * sizeof(adcsample_t));
                     }
                     break;
+
+                // 'R' - Begin continuous sampling/conversion of the ADC. Samples will go through
+                //       the conversion code, and will be sent out over the DAC.
                 case 'R':
+                    //if (run_status != RunStatus::Idle)
+                    //    break;
+
                     run_status = RunStatus::Converting;
                     dac_samples.fill(0);
                     adc::read_start(signal_operate, &adc_samples[0], adc_samples.size());
                     dac::write_start(&dac_samples[0], dac_samples.size());
                     break;
+
+                // 's' - Sends the current contents of the DAC buffer back over USB.
                 case 's':
-                    usbserial::write(dac_samples.data(), dac_samples.size() * sizeof(adcsample_t));
+                    usbserial::write(dac_samples.data(), 1/*dac_samples.size()*/ * sizeof(dacsample_t));
                     break;
+
+                // 'S' - Stops the continuous sampling/conversion.
                 case 'S':
+                    //if (run_status != RunStatus::Converting)
+                    //    break;
+
                     dac::write_stop();
                     adc::read_stop();
                     run_status = RunStatus::Idle;
                     break;
+
+                // 'e' - Reads in and loads the compiled conversion code binary from USB.
                 case 'e':
+                    // Get the binary's size
                     if (usbserial::read(&cmd[1], 2) < 2)
                         break;
-                    if (unsigned int count = cmd[1] | (cmd[2] << 8); count < sizeof(elf_file_store)) {
-                        usbserial::read(elf_file_store, count);
-                        elf_entry = elf::load(elf_file_store, elf_exec_store);
+
+                    // Only load the binary if it can fit in the memory reserved for it.
+                    if (unsigned int binarySize = cmd[1] | (cmd[2] << 8); binarySize < sizeof(elf_file_store)) {
+                        usbserial::read(elf_file_store, binarySize);
+                        elf_entry = elf::load(elf_file_store);
                     }
                     break;
+
+                // 'W' - Sets the number of samples for DAC writing with command 'w'.
+                //       If the provided count is zero, DAC writing is stopped.
                 case 'W':
                     if (usbserial::read(&cmd[1], 2) < 2)
                         break;
-                    if (auto count = std::min(static_cast<unsigned int>(cmd[1] | (cmd[2] << 8)), dac_samples.size()); count > 0)
-                        dac_sample_count = count;
-                    else
-                        dac::write_stop();
+                    if (unsigned int sampleCount = cmd[1] | (cmd[2] << 8); sampleCount <= dac_samples.size()) {
+                        if (sampleCount > 0)
+                            dac_sample_count = sampleCount;
+                        else
+                            dac::write_stop();
+                    }
                     break;
+
+                // 'w' - Starts the DAC, looping over the given data (data size set by command 'W').
                 case 'w':
-                    if (usbserial::read(&dac_samples[0], 2 * dac_sample_count) != 2 * dac_sample_count)
+                    if (usbserial::read(&dac_samples[0], dac_sample_count * sizeof(dacsample_t) !=
+                        dac_sample_count * sizeof(dacsample_t)))
+                    {
                         break;
-                    dac::write_start(&dac_samples[0], dac_sample_count);
+                    } else {
+                        dac::write_start(&dac_samples[0], dac_sample_count);
+                    }
                     break;
-                case 'i': // Identify ourself as an stmdsp device
+
+                // 'i' - Sends an identifying string to confirm that this is the stmdsp device.
+                case 'i':
                     usbserial::write("stmdsp", 6);
                     break;
-                case 'I': // Info (i.e. run status)
-                    usbserial::write(&run_status, 1);
+
+                // 'I' - Sends the current run status.
+                case 'I':
+                    usbserial::write(&run_status, sizeof(run_status));
                     break;
+
                 default:
                     break;
                 }
@@ -157,22 +202,26 @@ THD_FUNCTION(conversionThread, arg)
     while (1) {
         msg_t message;
         if (chMBFetchTimeout(&conversionMB, &message, TIME_INFINITE) == MSG_OK) {
-            auto samples = &adc_samples[0];
+            adcsample_t *samples = nullptr;
             auto halfsize = adc_samples.size() / 2;
             if (message == MSG_CONVFIRST) {
                 if (elf_entry)
-                    elf_entry(samples, halfsize);
+                    samples = elf_entry(&adc_samples[0], halfsize);
+                if (!samples)
+                    samples = &adc_samples[0];
                 std::copy(samples, samples + halfsize, &dac_samples[0]);
             } else if (message == MSG_CONVSECOND) {
                 if (elf_entry)
-                    elf_entry(samples + halfsize, halfsize);
-                std::copy(samples + halfsize, samples + halfsize * 2, &dac_samples[1024]);
+                    samples = elf_entry(&adc_samples[adc_samples.size() / 2], halfsize);
+                if (!samples)
+                    samples = &adc_samples[adc_samples.size() / 2];
+                std::copy(samples, samples + halfsize, &dac_samples[dac_samples.size() / 2]);
             }
         }
     }
 }
 
-void signal_operate(adcsample_t *buffer, size_t count)
+void signal_operate(adcsample_t *buffer, [[maybe_unused]] size_t count)
 {
     if (chMBGetUsedCountI(&conversionMB) > 1)
         conversion_abort();
@@ -185,22 +234,32 @@ extern "C" {
 __attribute__((naked))
 void HardFault_Handler()
 {
-    asm("push {lr}");
+    //asm("push {lr}");
 
     uint32_t *stack;
-    asm("mrs %0, psp" : "=r" (stack));
+    uint32_t lr;
+	asm("\
+		tst lr, #4; \
+		ite eq; \
+		mrseq %0, msp; \
+		mrsne %0, psp; \
+        mov %1, lr; \
+	" : "=r" (stack), "=r" (lr));
     //stack++;
     stack[7] |= (1 << 24); // Keep Thumb mode enabled
 
     conversion_abort();
 
+    // TODO test lr and decide how to recover
+
     //if (run_status == RunStatus::Converting) {
-    //    stack[6] = stack[5];   // Escape from elf_entry code
+        stack[6] = stack[5];   // Escape from elf_entry code
     //} else /*if (run_status == RunStatus::Recovered)*/ {
-        stack[6] = (uint32_t)main_loop & ~1; // Return to safety
+    //    stack[6] = (uint32_t)main_loop & ~1; // Return to safety
     //}
 
-    asm("pop {lr}; bx lr");
+    //asm("pop {lr}; bx lr");
+    asm("bx lr");
 }
 
 } // extern "C"