Initial Release

src/rp2_common/pico_stdio_semihosting/CMakeLists.txt

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+add_library(pico_stdio_semihosting INTERFACE)
+
+target_sources(pico_stdio_semihosting INTERFACE
+        ${CMAKE_CURRENT_LIST_DIR}/stdio_semihosting.c
+)
+
+target_include_directories(pico_stdio_semihosting INTERFACE ${CMAKE_CURRENT_LIST_DIR}/include)
+
+target_compile_definitions(pico_stdio_semihosting INTERFACE
+        PICO_STDIO_SEMIHOSTING=1
+)
+
+target_link_libraries(pico_stdio_semihosting INTERFACE pico_stdio)

src/rp2_common/pico_stdio_semihosting/include/pico/stdio_semihosting.h

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+/*
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef _PICO_STDIO_SEMIHOSTING_H
+#define _PICO_STDIO_SEMIHOSTING_H
+
+#include "pico/stdio.h"
+
+/** \brief Experimental support for stdout using RAM semihosting
+ *  \defgroup pico_stdio_semihosting pico_stdio_semihosting
+ *  \ingroup pico_stdio
+ *
+ *  Linking this library or calling `pico_enable_stdio_semihosting(TARGET)` in the CMake (which
+ *  achieves the same thing) will add semihosting to the drivers used for standard output
+ */
+
+// PICO_CONFIG: PICO_STDIO_SEMIHOSTING_DEFAULT_CRLF, Default state of CR/LF translation for semihosting output, type=bool, default=PICO_STDIO_DEFAULT_CRLF, group=pico_stdio_semihosting
+#ifndef PICO_STDIO_SEMIHOSTING_DEFAULT_CRLF
+#define PICO_STDIO_SEMIHOSTING_DEFAULT_CRLF PICO_STDIO_DEFAULT_CRLF
+#endif
+
+extern stdio_driver_t stdio_semihosting;
+
+/*! \brief Explicitly initialize stdout over semihosting and add it to the current set of stdout targets
+ *  \ingroup pico_stdio_semihosting
+ *
+ * \note this method is automatically called by \ref stdio_init_all() if `pico_stdio_semihosting` is included in the build
+ */
+void stdio_semihosting_init();
+
+#endif

src/rp2_common/pico_stdio_semihosting/stdio_semihosting.c

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+/*
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include "pico/stdio/driver.h"
+#include "pico/stdio_semihosting.h"
+#include "pico/binary_info.h"
+
+//static void __attribute__((naked)) semihosting_puts(const char *s) {
+//    __asm (
+//
+//    "mov r1, r0\n"
+//    "mov r0, #4\n"
+//    "bkpt 0xab\n"
+//    "bx lr\n"
+//    );
+//}
+
+static void __attribute__((naked)) semihosting_putc(char c) {
+    __asm (
+
+    "mov r1, r0\n"
+    "mov r0, #3\n"
+    "bkpt 0xab\n"
+    "bx lr\n"
+    );
+}
+
+
+static void stdio_semihosting_out_chars(const char *buf, int length) {
+    for (uint i = 0; i <length; i++) {
+        semihosting_putc(buf[i]);
+    }
+}
+
+stdio_driver_t stdio_semihosting = {
+        .out_chars = stdio_semihosting_out_chars,
+#if PICO_STDIO_ENABLE_CRLF_SUPPORT
+        .crlf_enabled = PICO_STDIO_SEMIHOSTING_DEFAULT_CRLF
+#endif
+};
+
+void stdio_semihosting_init() {
+#if !PICO_NO_BI_STDIO_SEMIHOSTING
+    bi_decl_if_func_used(bi_program_feature("semihosting stdout"));
+#endif
+    stdio_set_driver_enabled(&stdio_semihosting, true);
+}
+