添加rtthread相关代码

riscv/rtthread/components/libc/compilers/picolibc/syscall.c

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2006-2023, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2023-05-17     Flybreak     the first version
+ */
+
+#include <rtthread.h>
+#include <sys/types.h>
+
+/* global errno */
+static volatile int __pico_errno;
+
+int *pico_get_errno(void)
+{
+    rt_thread_t tid = RT_NULL;
+
+    if (rt_interrupt_get_nest() != 0)
+    {
+        /* it's in interrupt context */
+        return (int *)&__pico_errno;
+    }
+
+    tid = rt_thread_self();
+    if (tid == RT_NULL)
+    {
+        return (int *)&__pico_errno;
+    }
+
+    return (int *)&tid->error;
+}
+
+#ifdef RT_USING_HEAP
+void *malloc(size_t n)
+{
+    return rt_malloc(n);
+}
+RTM_EXPORT(malloc);
+
+void *realloc(void *rmem, size_t newsize)
+{
+    return rt_realloc(rmem, newsize);
+}
+RTM_EXPORT(realloc);
+
+void *calloc(size_t nelem, size_t elsize)
+{
+    return rt_calloc(nelem, elsize);
+}
+RTM_EXPORT(calloc);
+
+void free(void *rmem)
+{
+    rt_free(rmem);
+}
+RTM_EXPORT(free);
+#endif /* RT_USING_HEAP */