From 3282a756679019fd723346cc3bc584cc582eb669 Mon Sep 17 00:00:00 2001
From: Oxore <oxore@protonmail.com>
Date: Tue, 7 Mar 2023 19:10:25 +0300
Subject: Begin implementing serial descriptors

---
 app/platform/stm32f0-gcc/retarget.cpp | 82 +++++++++++++++++++++++++++++------
 1 file changed, 69 insertions(+), 13 deletions(-)

(limited to 'app/platform/stm32f0-gcc/retarget.cpp')

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)
-- 
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