merge elf loading and adc streaming

13 files changed, 388 insertions, 157 deletions

diff --git a/.gitignore b/.gitignore
index c24aa5f..d01aefe 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,5 +3,6 @@ ChibiOS_*
 **/.*
 gui/stmdspgui
 **/*.o
+**/*.so
 perf*
 
diff --git a/filter/Makefile b/filter/Makefile
new file mode 100644
index 0000000..a1ce186
--- /dev/null
+++ b/filter/Makefile
@@ -0,0 +1,14 @@
+all:
+	@arm-none-eabi-gcc -mcpu=cortex-m4 -mthumb -Os --specs=nosys.specs -nostartfiles -fPIE -c test.cpp
+	@arm-none-eabi-ld -shared -n -N -z max-page-size=512 -Ttext-segment=0 \
+	    test.o -o test.so
+	@arm-none-eabi-strip -s -S --strip-unneeded test.so
+	@arm-none-eabi-objcopy --remove-section .dynsym \
+						   --remove-section .dynstr \
+						   --remove-section .dynamic \
+						   --remove-section .hash \
+						   --remove-section .ARM.exidx \
+						   --remove-section .ARM.attributes \
+						   --remove-section .comment \
+						   test.so
+
diff --git a/filter/test.cpp b/filter/test.cpp
new file mode 100644
index 0000000..0953539
--- /dev/null
+++ b/filter/test.cpp
@@ -0,0 +1,15 @@
+#include <cstdint>
+
+using adcsample_t = uint16_t;
+__attribute__((section(".process_data")))
+void process_data(adcsample_t *samples, unsigned int size);
+ 
+////////////////////////////////////////////////////////////////////////////////
+
+void process_data(adcsample_t *samples, unsigned int size)
+{
+    size--;
+    for (unsigned int i = 0; i < size; i++)
+        samples[i] = samples[i] * 80 / 100  + samples[i + 1] * 20 / 100;
+}
+
diff --git a/source/adc.cpp b/source/adc.cpp
index e754e0e..f2903c3 100644
--- a/source/adc.cpp
+++ b/source/adc.cpp
@@ -18,7 +18,7 @@ constexpr static const ADCConfig adc_config = {
     .difsel = 0
 };
 
-void adc_read_callback(ADCDriver *);
+static void adc_read_callback(ADCDriver *);
 
 /*constexpr*/ static ADCConversionGroup adc_group_config = {
     .circular = false,
@@ -45,51 +45,88 @@ constexpr static const GPTConfig gpt_config = {
 };
 
 static bool adc_is_read_finished = false;
-static bool adc_is_read_continuous = false;
 static adcsample_t *adc_current_buffer = nullptr;
 static size_t adc_current_buffer_size = 0;
-static adc_operation_t adc_operation_func = nullptr;
+static adc::operation_t adc_operation_func = nullptr;
 
-void adc_init()
+namespace adc
 {
-    palSetPadMode(GPIOA, 0, PAL_MODE_INPUT_ANALOG);
-
-    gptStart(gptd, &gpt_config);
-    adcStart(adcd, &adc_config);
-    adcSTM32EnableVREF(adcd);
-}
-
-adcsample_t *adc_read(adcsample_t *buffer, size_t count)
-{
-    adc_is_read_finished = false;
-    adc_is_read_continuous = false;
-    adc_group_config.circular = false;
-    adcStartConversion(adcd, &adc_group_config, buffer, count);
-    gptStartContinuous(gptd, 100); // 10kHz
-    while (!adc_is_read_finished);
-    return buffer;
-}
-
-void adc_read_start(adc_operation_t operation_func, adcsample_t *buffer, size_t count)
-{
-    adc_is_read_continuous = true;
-    adc_current_buffer = buffer;
-    adc_current_buffer_size = count;
-    adc_operation_func = operation_func;
-    adc_group_config.circular = true;
-    adcStartConversion(adcd, &adc_group_config, buffer, count);
-    gptStartContinuous(gptd, 100); // 10kHz
-}
+    void init()
+    {
+        palSetPadMode(GPIOA, 0, PAL_MODE_INPUT_ANALOG);
+    
+        gptStart(gptd, &gpt_config);
+        adcStart(adcd, &adc_config);
+        adcSTM32EnableVREF(adcd);
+    }
+    
+    adcsample_t *read(adcsample_t *buffer, size_t count)
+    {
+        adc_is_read_finished = false;
+        adc_group_config.circular = false;
+        adcStartConversion(adcd, &adc_group_config, buffer, count);
+        gptStartContinuous(gptd, 100); // 10kHz
+        while (!adc_is_read_finished);
+        return buffer;
+    }
 
-void adc_read_stop()
-{
-    adc_is_read_continuous = false;
-    gptStopTimer(gptd);
+    void read_start(operation_t operation_func, adcsample_t *buffer, size_t count)
+    {
+        adc_current_buffer = buffer;
+        adc_current_buffer_size = count;
+        adc_operation_func = operation_func;
+        adc_group_config.circular = true;
+        adcStartConversion(adcd, &adc_group_config, buffer, count);
+        gptStartContinuous(gptd, 100); // 10kHz
+    }
+    
+    void read_stop()
+    {
+        gptStopTimer(gptd);
+        adc_group_config.circular = false;
+        adc_current_buffer = nullptr;
+        adc_current_buffer_size = 0;
+        adc_operation_func = nullptr;
+    }
+ 
+    void set_rate(rate r)
+    {
+        uint32_t val = 0;
+    
+        switch (r) {
+        case rate::R2P5:
+            val = ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_2P5);
+            break;
+        case rate::R6P5:
+            val = ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_6P5);
+            break;
+        case rate::R12P5:
+            val = ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_12P5);
+            break;
+        case rate::R24P5:
+            val = ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_24P5);
+            break;
+        case rate::R47P5:
+            val = ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_47P5);
+            break;
+        case rate::R92P5:
+            val = ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_92P5);
+            break;
+        case rate::R247P5:
+            val = ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_247P5);
+            break;
+        case rate::R640P5:
+            val = ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_640P5);
+            break;
+        }
+    
+        adc_group_config.smpr[0] = val;
+    }
 }
 
 void adc_read_callback(ADCDriver *driver)
 {
-    if (!adc_is_read_continuous) {
+    if (!adc_group_config.circular) {
         gptStopTimer(gptd);
         adc_is_read_finished = true;
     } else if (adc_operation_func != nullptr) {
@@ -104,37 +141,3 @@ void adc_read_callback(ADCDriver *driver)
     }
 }
 
-void adc_set_rate(ADCRate rate)
-{
-    uint32_t val = 0;
-
-    switch (rate) {
-    case ADCRate::R2P5:
-        val = ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_2P5);
-        break;
-    case ADCRate::R6P5:
-        val = ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_6P5);
-        break;
-    case ADCRate::R12P5:
-        val = ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_12P5);
-        break;
-    case ADCRate::R24P5:
-        val = ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_24P5);
-        break;
-    case ADCRate::R47P5:
-        val = ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_47P5);
-        break;
-    case ADCRate::R92P5:
-        val = ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_92P5);
-        break;
-    case ADCRate::R247P5:
-        val = ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_247P5);
-        break;
-    case ADCRate::R640P5:
-        val = ADC_SMPR1_SMP_AN5(ADC_SMPR_SMP_640P5);
-        break;
-    }
-
-    adc_group_config.smpr[0] = val;
-}
-
diff --git a/source/adc.hpp b/source/adc.hpp
index 15e343a..376b156 100644
--- a/source/adc.hpp
+++ b/source/adc.hpp
@@ -14,24 +14,27 @@
 
 #include "hal.h"
 
-enum class ADCRate {
-    R2P5,
-    R6P5,
-    R12P5,
-    R24P5,
-    R47P5,
-    R92P5,
-    R247P5,
-    R640P5
-};
+namespace adc
+{
+    using operation_t = void (*)(adcsample_t *buffer, size_t count);
 
-using adc_operation_t = void (*)(adcsample_t *buffer, size_t count);
-
-void adc_init();
-adcsample_t *adc_read(adcsample_t *buffer, size_t count);
-void adc_read_start(adc_operation_t operation_func, adcsample_t *buffer, size_t count);
-void adc_read_stop();
-void adc_set_rate(ADCRate rate);
+    enum class rate {
+        R2P5,
+        R6P5,
+        R12P5,
+        R24P5,
+        R47P5,
+        R92P5,
+        R247P5,
+        R640P5
+    };
+    
+    void init();
+    adcsample_t *read(adcsample_t *buffer, size_t count);
+    void read_start(operation_t operation_func, adcsample_t *buffer, size_t count);
+    void read_stop();
+    void set_rate(rate r);
+}
 
 #endif // STMDSP_ADC_HPP_
 
diff --git a/source/dac.cpp b/source/dac.cpp
index d2bcf37..6096d8e 100644
--- a/source/dac.cpp
+++ b/source/dac.cpp
@@ -34,24 +34,27 @@ constexpr static const GPTConfig gpt_config = {
   .dier = 0
 };
 
-void dac_init()
+namespace dac
 {
-    palSetPadMode(GPIOA, 4, PAL_MODE_INPUT_ANALOG);
-    //palSetPadMode(GPIOA, 5, PAL_MODE_INPUT_ANALOG);
-
-    dacStart(dacd, &dac_config);
-    gptStart(gptd, &gpt_config);
-}
-
-void dac_write_start(dacsample_t *buffer, size_t count)
-{
-    dacStartConversion(dacd, &dac_group_config, buffer, count);
-    gptStartContinuous(gptd, 1);
-}
-
-void dac_write_stop()
-{
-    gptStopTimer(gptd);
-    dacStopConversion(dacd);
+    void init()
+    {
+        palSetPadMode(GPIOA, 4, PAL_MODE_INPUT_ANALOG);
+        //palSetPadMode(GPIOA, 5, PAL_MODE_INPUT_ANALOG);
+    
+        dacStart(dacd, &dac_config);
+        gptStart(gptd, &gpt_config);
+    }
+    
+    void write_start(dacsample_t *buffer, size_t count)
+    {
+        dacStartConversion(dacd, &dac_group_config, buffer, count);
+        gptStartContinuous(gptd, 1);
+    }
+    
+    void write_stop()
+    {
+        gptStopTimer(gptd);
+        dacStopConversion(dacd);
+    }
 }
 
diff --git a/source/dac.hpp b/source/dac.hpp
index ce67f40..9d529bf 100644
--- a/source/dac.hpp
+++ b/source/dac.hpp
@@ -14,9 +14,12 @@
 
 #include "hal.h"
 
-void dac_init();
-void dac_write_start(dacsample_t *buffer, size_t count);
-void dac_write_stop();
+namespace dac
+{
+    void init();
+    void write_start(dacsample_t *buffer, size_t count);
+    void write_stop();
+}
 
 #endif // STMDSP_DAC_HPP_
 
diff --git a/source/elf_format.hpp b/source/elf_format.hpp
new file mode 100644
index 0000000..ed74c7b
--- /dev/null
+++ b/source/elf_format.hpp
@@ -0,0 +1,93 @@
+#ifndef STMDSP_ELF_FORMAT_HPP_
+#define STMDSP_ELF_FORMAT_HPP_
+
+#include <cstdint>
+
+#define EI_NIDENT 16
+
+#define PT_NULL     0
+#define PT_LOAD     1
+#define PT_DYNAMIC  2
+#define PT_INTERP   3
+#define PT_NOTE     4
+#define PT_SHLIB    5
+#define PT_PHDR     6
+#define PT_RESERVED 0x70000000
+
+#define ELF32_ST_BIND(i)    ((i) >> 4)
+#define ELF32_ST_TYPE(i)    ((i) & 0xF)
+#define ELF32_ST_INFO(b, t) (((b) << 4) + ((t) & 0xF))
+
+#define ELF32_R_SYM(i)     ((i) >> 8)
+#define ELF32_R_TYPE(i)    ((i) & 0xFF)
+#define ELF32_R_INFO(s, t) (((s) << 8) + ((t) & 0xFF))
+
+typedef uint32_t Elf32_Addr;
+typedef uint16_t Elf32_Half;
+typedef uint32_t Elf32_Off;
+typedef uint32_t Elf32_Sword;
+typedef uint32_t Elf32_Word;
+
+typedef struct {
+	unsigned char e_ident[EI_NIDENT];
+	Elf32_Half    e_type;
+	Elf32_Half    e_machine;
+	Elf32_Word    e_version;
+	Elf32_Addr    e_entry;
+	Elf32_Off     e_phoff;
+	Elf32_Off     e_shoff;
+	Elf32_Word    e_flags;
+	Elf32_Half    e_ehsize;
+	Elf32_Half    e_phentsize;
+	Elf32_Half    e_phnum;
+	Elf32_Half    e_shentsize;
+	Elf32_Half    e_shnum;
+	Elf32_Half    e_shstrndx;
+} __attribute__((packed)) Elf32_Ehdr;
+
+typedef struct {
+	Elf32_Word sh_name;
+	Elf32_Word sh_type;
+	Elf32_Word sh_flags;
+	Elf32_Addr sh_addr;
+	Elf32_Off  sh_offset;
+	Elf32_Word sh_size;
+	Elf32_Word sh_link;
+	Elf32_Word sh_info;
+	Elf32_Word sh_addralign;
+	Elf32_Word sh_entsize;
+} __attribute__((packed)) Elf32_Shdr;
+
+typedef struct {
+	Elf32_Word    st_name;
+	Elf32_Addr    st_value;
+	Elf32_Word    st_size;
+	unsigned char st_info;
+	unsigned char st_other;
+	Elf32_Half    st_shndx;
+} __attribute__((packed)) Elf32_Sym;
+
+typedef struct {
+	Elf32_Addr r_offset;
+	Elf32_Word r_info;
+} __attribute__((packed)) Elf32_Rel;
+
+typedef struct {
+	Elf32_Addr  r_offset;
+	Elf32_Word  r_info;
+	Elf32_Sword r_addend;
+} __attribute__((packed)) Elf32_Rela;
+
+typedef struct {
+	Elf32_Word p_type;
+	Elf32_Off  p_offset;
+	Elf32_Addr p_vaddr;
+	Elf32_Addr p_paddr;
+	Elf32_Word p_filesz;
+	Elf32_Word p_memsz;
+	Elf32_Word p_flags;
+	Elf32_Word p_align;
+} __attribute__((packed)) Elf32_Phdr;
+
+#endif // STMDSP_ELF_FORMAT_HPP_
+
diff --git a/source/elf_load.cpp b/source/elf_load.cpp
new file mode 100644
index 0000000..661dbc3
--- /dev/null
+++ b/source/elf_load.cpp
@@ -0,0 +1,77 @@
+#include "elf_load.hpp"
+#include "elf_format.hpp"
+
+#include <algorithm>
+#include <cstring>
+
+extern void *elf_load_offset;
+static const unsigned char elf_header[] = { '\177', 'E', 'L', 'F' };
+
+template<typename T>
+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);
+
+namespace elf {
+
+entry_t elf_load(void *elf_data)
+{
+    auto ehdr = reinterpret_cast<Elf32_Ehdr *>(elf_data);
+    if (std::equal(ehdr->e_ident, ehdr->e_ident + 4, elf_header))
+        return nullptr;
+
+    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;
+        }
+    }
+
+    // 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);
+}
+
+} // 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;
+}
+
diff --git a/source/elf_load.hpp b/source/elf_load.hpp
new file mode 100644
index 0000000..722b19b
--- /dev/null
+++ b/source/elf_load.hpp
@@ -0,0 +1,12 @@
+#ifndef ELF_LOAD_HPP_
+#define ELF_LOAD_HPP_
+
+namespace elf
+{
+    using entry_t = void (*)();
+
+    entry_t load(void *file_data);
+}
+
+#endif // ELF_LOAD_HPP_
+
diff --git a/source/main.cpp b/source/main.cpp
index 07c73ba..f1170a6 100644
--- a/source/main.cpp
+++ b/source/main.cpp
@@ -35,45 +35,45 @@ int main()
 
     palSetPadMode(GPIOA, 5,  PAL_MODE_OUTPUT_PUSHPULL); // LED
 
-    adc_init();
-    dac_init();
-    usbserial_init();
+    adc::init();
+    dac::init();
+    usbserial::init();
 
     static unsigned int dac_sample_count = 2048;
 	while (true) {
-        if (usbserial_is_active()) {
+        if (usbserial::is_active()) {
             // Expect to receive a byte command 'packet'.
-            if (char cmd[3]; usbserial_read(&cmd, 1) > 0) {
+            if (char cmd[3]; usbserial::read(&cmd, 1) > 0) {
                 switch (cmd[0]) {
                 case 'r': // Read in analog signal
-                    if (usbserial_read(&cmd[1], 2) < 2)
+                    if (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));
+                        adc::read(&adc_samples[0], count);
+                        usbserial::write(adc_samples.data(), count * sizeof(adcsample_t));
                     }
                     break;
                 case 'R':
-                    adc_read_start(signal_operate, &adc_samples[0], adc_samples.size() * sizeof(adcsample_t));
+                    adc::read_start(signal_operate, &adc_samples[0], adc_samples.size() * sizeof(adcsample_t));
                     break;
                 case 'S':
-                    adc_read_stop();
+                    adc::read_stop();
                     break;
                 case 'W':
-                    if (usbserial_read(&cmd[1], 2) < 2)
+                    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();
+                        dac::write_stop();
                     break;
                 case 'w':
-                    if (usbserial_read(&dac_samples[0], 2 * dac_sample_count) != 2 * dac_sample_count)
+                    if (usbserial::read(&dac_samples[0], 2 * dac_sample_count) != 2 * dac_sample_count)
                         break;
-                    dac_write_start(&dac_samples[0], dac_sample_count);
+                    dac::write_start(&dac_samples[0], dac_sample_count);
                     break;
                 case 'i': // Identify ourself as an stmdsp device
-                    usbserial_write("stmdsp", 6);
+                    usbserial::write("stmdsp", 6);
                     break;
                 default:
                     break;
diff --git a/source/usbserial.cpp b/source/usbserial.cpp
index 5d605e6..ec2fc5d 100644
--- a/source/usbserial.cpp
+++ b/source/usbserial.cpp
@@ -15,35 +15,38 @@
 
 constexpr static const auto sdud = &SDU1;
 
-void usbserial_init()
+namespace usbserial
 {
-    palSetPadMode(GPIOA, 11, PAL_MODE_ALTERNATE(10));
-    palSetPadMode(GPIOA, 12, PAL_MODE_ALTERNATE(10));
-
-    sduObjectInit(sdud);
-    sduStart(sdud, &serusbcfg);
-
-    // Reconnect bus so device can re-enumerate on reset
-    usbDisconnectBus(serusbcfg.usbp);
-    chThdSleepMilliseconds(1500);
-    usbStart(serusbcfg.usbp, &usbcfg);
-    usbConnectBus(serusbcfg.usbp);
-}
-
-bool usbserial_is_active()
-{
-    return sdud->config->usbp->state == USB_ACTIVE;
-}
-
-size_t usbserial_read(void *buffer, size_t count)
-{
-    auto bss = reinterpret_cast<BaseSequentialStream *>(sdud);
-    return streamRead(bss, static_cast<uint8_t *>(buffer), count);
-}
-
-size_t usbserial_write(const void *buffer, size_t count)
-{
-    auto bss = reinterpret_cast<BaseSequentialStream *>(sdud);
-    return streamWrite(bss, static_cast<const uint8_t *>(buffer), count);
+    void init()
+    {
+        palSetPadMode(GPIOA, 11, PAL_MODE_ALTERNATE(10));
+        palSetPadMode(GPIOA, 12, PAL_MODE_ALTERNATE(10));
+    
+        sduObjectInit(sdud);
+        sduStart(sdud, &serusbcfg);
+    
+        // Reconnect bus so device can re-enumerate on reset
+        usbDisconnectBus(serusbcfg.usbp);
+        chThdSleepMilliseconds(1500);
+        usbStart(serusbcfg.usbp, &usbcfg);
+        usbConnectBus(serusbcfg.usbp);
+    }
+    
+    bool is_active()
+    {
+        return sdud->config->usbp->state == USB_ACTIVE;
+    }
+    
+    size_t read(void *buffer, size_t count)
+    {
+        auto bss = reinterpret_cast<BaseSequentialStream *>(sdud);
+        return streamRead(bss, static_cast<uint8_t *>(buffer), count);
+    }
+    
+    size_t write(const void *buffer, size_t count)
+    {
+        auto bss = reinterpret_cast<BaseSequentialStream *>(sdud);
+        return streamWrite(bss, static_cast<const uint8_t *>(buffer), count);
+    }
 }
 
diff --git a/source/usbserial.hpp b/source/usbserial.hpp
index 4b0eab2..4c33d51 100644
--- a/source/usbserial.hpp
+++ b/source/usbserial.hpp
@@ -14,10 +14,14 @@
 
 #include "hal.h"
 
-void usbserial_init();
-bool usbserial_is_active();
-size_t usbserial_read(void *buffer, size_t count);
-size_t usbserial_write(const void *buffer, size_t count);
+namespace usbserial
+{
+    void init();
+    bool is_active();
+
+    size_t read(void *buffer, size_t count);
+    size_t write(const void *buffer, size_t count);
+}
 
 #endif // STMDSP_USBSERIAL_HPP_