firmware/ice40-riscv: Import common parts to all iCE40/RISC-V firmwares

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/firmware/ice40-riscv/common/mini-printf.h b/firmware/ice40-riscv/common/mini-printf.h
new file mode 100644
index 0000000..99a9519
--- /dev/null
+++ b/firmware/ice40-riscv/common/mini-printf.h
@@ -0,0 +1,50 @@
+/*
+ * The Minimal snprintf() implementation
+ *
+ * Copyright (c) 2013 Michal Ludvig <michal@logix.cz>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of the auhor nor the names of its contributors
+ *       may be used to endorse or promote products derived from this software
+ *       without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+
+#ifndef __MINI_PRINTF__
+#define __MINI_PRINTF__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdarg.h>
+
+int mini_vsnprintf(char* buffer, unsigned int buffer_len, const char *fmt, va_list va);
+int mini_snprintf(char* buffer, unsigned int buffer_len, const char *fmt, ...);
+
+#ifdef __cplusplus
+}
+#endif
+
+#define vsnprintf mini_vsnprintf
+#define snprintf mini_snprintf
+
+#endif