Begin implementing serial descriptors

5 files changed, 117 insertions, 15 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c4a7808..224e421 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -74,6 +74,7 @@ set(nixie_clock_sources
     "app/main.c"
     "app/stm32f0xx_it.c"
     "app/system_stm32f0xx.c"
+    "app/platform/stm32f0-gcc/uart.cpp"
     "app/platform/stm32f0-gcc/retarget.cpp"
     "app/platform/stm32f0-gcc/freertos/port.c"
     "app/platform/stm32f0-gcc/startup/handlers_cm.c"
diff --git a/app/platform/stm32f0-gcc/retarget.cpp b/app/platform/stm32f0-gcc/retarget.cpp
index 524840e..8b8160f 100644
--- a/app/platform/stm32f0-gcc/retarget.cpp
+++ b/app/platform/stm32f0-gcc/retarget.cpp
@@ -4,11 +4,40 @@
 #include <cstdlib>
 #include <cerrno>
 #include "third_party/printf/printf.h"
+#include "fcntl.h"
+#include "uart.h"
 
 #ifdef errno
 #undef errno
 #endif
 
+#if defined(__GNUC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wold-style-cast"
+#endif
+
+enum class FileType {
+    kUART,
+    kUARTDirect,
+};
+
+struct File
+{
+    FileType type;
+    int flags;
+    void *extra;
+};
+
+static constexpr size_t kFilesCount = 5;
+
+static File files[5] {
+    { FileType::kUART, O_NONBLOCK, reinterpret_cast<void *>(USART1), },
+    { FileType::kUART, O_NONBLOCK, reinterpret_cast<void *>(USART1), },
+    { FileType::kUARTDirect, 0, reinterpret_cast<void *>(USART1), },
+    { FileType::kUART, O_NONBLOCK, reinterpret_cast<void *>(USART3), },
+    { FileType::kUART, O_NONBLOCK, reinterpret_cast<void *>(USART4), },
+};
+
 int errno{};
 
 extern "C" [[noreturn]] void vApplicationMallocFailedHook(void)
@@ -45,25 +74,52 @@ extern "C" [[noreturn]] void __assert_func (
   /* NOTREACHED */
 }
 
+static File* FileOfDescriptor(int fd)
+{
+    if (fd < 0 || static_cast<unsigned>(fd) >= kFilesCount)
+        return nullptr;
+    return files + fd;
+}
+
 extern "C" ssize_t read(int fd, void *buf, size_t nbytes)
 {
-    (void) fd;
-    (void) buf;
-    (void) nbytes;
-    errno = ENOSYS;
-    return -1;
+    File* file = FileOfDescriptor(fd);
+    if (file == nullptr) {
+        errno = EBADF;
+        return -1;
+    }
+    size_t ret{};
+    switch (file->type) {
+    case FileType::kUART:
+        ret = UARTRead(reinterpret_cast<USART_TypeDef*>(file->extra), buf, nbytes);
+        break;
+    case FileType::kUARTDirect:
+        ret = UARTReadDirect(reinterpret_cast<USART_TypeDef*>(file->extra), buf, nbytes);
+        break;
+    }
+    return ret;
 }
 
 extern "C" ssize_t write(int fd, const void *buf, size_t nbytes)
 {
-    (void) fd;
-    (void) buf;
-    (void) nbytes;
-    errno = ENOSYS;
-    return -1;
+    File* file = FileOfDescriptor(fd);
+    if (file == nullptr) {
+        errno = EBADF;
+        return -1;
+    }
+    size_t ret{};
+    switch (file->type) {
+    case FileType::kUART:
+        ret = UARTWrite(reinterpret_cast<USART_TypeDef*>(file->extra), buf, nbytes);
+        break;
+    case FileType::kUARTDirect:
+        ret = UARTWriteDirect(reinterpret_cast<USART_TypeDef*>(file->extra), buf, nbytes);
+        break;
+    }
+    return ret;
 }
 
-static void dputchar2(char c, void* fd)
+static void dputchar(char c, void* fd)
 {
     write(reinterpret_cast<int>(fd), &c, 1);
 }
@@ -77,14 +133,14 @@ extern "C" int dprintf(int fd, const char * format, ...)
 {
     va_list args;
     va_start(args, format);
-    const int ret = vfctprintf(dputchar2, reinterpret_cast<void *>(fd), format, args);
+    const int ret = vfctprintf(dputchar, reinterpret_cast<void *>(fd), format, args);
     va_end(args);
     return ret;
 }
 
 extern "C" int vdprintf(int fd, const char * format, va_list args)
 {
-    return vfctprintf(dputchar2, reinterpret_cast<void *>(fd), format, args);
+    return vfctprintf(dputchar, reinterpret_cast<void *>(fd), format, args);
 }
 
 extern "C" void putchar_(char c)
diff --git a/app/platform/stm32f0-gcc/uart.cpp b/app/platform/stm32f0-gcc/uart.cpp
new file mode 100644
index 0000000..0fa6527
--- /dev/null
+++ b/app/platform/stm32f0-gcc/uart.cpp
@@ -0,0 +1,33 @@
+#include "uart.h"
+
+size_t UARTWrite(USART_TypeDef* uart, const void *data, size_t nbytes)
+{
+    if (uart == nullptr) return 0;
+    (void) data;
+    (void) nbytes;
+    return 0;
+}
+
+size_t UARTWriteDirect(USART_TypeDef* uart, const void *data, size_t nbytes)
+{
+    if (uart == nullptr) return 0;
+    (void) data;
+    (void) nbytes;
+    return 0;
+}
+
+size_t UARTRead(USART_TypeDef* uart, void *data, size_t nbytes)
+{
+    if (uart == nullptr) return 0;
+    (void) data;
+    (void) nbytes;
+    return 0;
+}
+
+size_t UARTReadDirect(USART_TypeDef* uart, void *data, size_t nbytes)
+{
+    if (uart == nullptr) return 0;
+    (void) data;
+    (void) nbytes;
+    return 0;
+}
diff --git a/app/platform/stm32f0-gcc/uart.h b/app/platform/stm32f0-gcc/uart.h
new file mode 100644
index 0000000..176f847
--- /dev/null
+++ b/app/platform/stm32f0-gcc/uart.h
@@ -0,0 +1,12 @@
+#pragma once
+#include <cstddef>
+#include "stm32f0xx.h"
+
+// Non-blocking buffered write
+size_t UARTWrite(USART_TypeDef*, const void *data, size_t nbytes);
+// Blocking write directly into data register
+size_t UARTWriteDirect(USART_TypeDef*, const void *data, size_t nbytes);
+// Non-blocking buffered read
+size_t UARTRead(USART_TypeDef*, void *data, size_t nbytes);
+// Blocking read directly from data register
+size_t UARTReadDirect(USART_TypeDef*, void *data, size_t nbytes);
diff --git a/third_party/CMSIS/Device/Include/cmsis_gcc.h b/third_party/CMSIS/Device/Include/cmsis_gcc.h
index d868f2e..11d9594 100644
--- a/third_party/CMSIS/Device/Include/cmsis_gcc.h
+++ b/third_party/CMSIS/Device/Include/cmsis_gcc.h
@@ -147,7 +147,7 @@ __attribute__( ( always_inline ) ) __STATIC_INLINE uint32_t __get_xPSR(void)
  */

 __attribute__( ( always_inline ) ) __STATIC_INLINE uint32_t __get_PSP(void)

 {

-  register uint32_t result;

+  uint32_t result;

 

   __ASM volatile ("MRS %0, psp\n"  : "=r" (result) );

   return(result);

@@ -172,7 +172,7 @@ __attribute__( ( always_inline ) ) __STATIC_INLINE void __set_PSP(uint32_t topOf
  */

 __attribute__( ( always_inline ) ) __STATIC_INLINE uint32_t __get_MSP(void)

 {

-  register uint32_t result;

+  uint32_t result;

 

   __ASM volatile ("MRS %0, msp\n" : "=r" (result) );

   return(result);