From 27ffa747f36aee9c1d5bbc61395a078238366070 Mon Sep 17 00:00:00 2001
From: Kimplul <kimi.h.kuparinen@gmail.com>
Date: Thu, 11 May 2023 22:55:31 +0300
Subject: arbitrary load address and RAM base detection

+ Both kind of go hand in hand, made sense to do both at the same time.

Some parts feel slightly hacky, the loader works by placing everything
on the stack and avoiding global values. Still, seems to work?
---
 lib/dbg_fdt.c | 159 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 159 insertions(+)
 create mode 100644 lib/dbg_fdt.c

(limited to 'lib/dbg_fdt.c')

diff --git a/lib/dbg_fdt.c b/lib/dbg_fdt.c
new file mode 100644
index 0000000..6d02442
--- /dev/null
+++ b/lib/dbg_fdt.c
@@ -0,0 +1,159 @@
+/* SPDX-License-Identifier: copyleft-next-0.3.1 */
+/* Copyright 2021 - 2022, Kim Kuparinen < kimi.h.kuparinen@gmail.com > */
+
+/**
+ * @file dbg_fdt.c
+ * Dump fdt info to serial.
+ */
+
+#include <kmi/debug.h>
+#include <libfdt.h>
+
+#if defined(DEBUG)
+/**
+ * Print single character \c depth number of times.
+ *
+ * @param c Character to print.
+ * @param depth Number of times to print character.
+ */
+static void __print_char(char c, int depth)
+{
+	/* lol, ugly but good enough for now */
+	for (int i = 0; i < depth; ++i)
+		dbg("%c", c);
+}
+
+/**
+ * Check if ASCII character is in printable range.
+ *
+ * In this case, printable is anything that isn't a control character, line
+ * feed, bell, etc.
+ *
+ * @param c Character to check.
+ * @return \ref true if in printable range, \ref false otherwise.
+ */
+static int __printable(char c)
+{
+	return (c >= 32) && (c <= 126);
+}
+
+/**
+ * Check if \c data and \c len bytes from it form a reasonable string.
+ *
+ * @param data Pointer to some binary data to check.
+ * @param len Assumed length of string.
+ * @return \c true if data is likely some string, \c false otherwise.
+ */
+static int __is_string(const void *data, int len)
+{
+	const char *s = data;
+
+	/* zero length is not */
+	if (len == 0)
+		return 0;
+
+	/* must terminate with zero or '\n' */
+	if (s[len - 1] != '\0' && s[len - 1] != '\n')
+		return 0;
+
+	/* printable or a null byte (concatenated strings) */
+	while (((*s == '\0') || __printable(*s)) && (len > 0)) {
+		/*
+		 * If we see a null, there are three possibilities:
+		 * 1) If len == 1, it is the end of the string, printable
+		 * 2) Next character also a null, not printable.
+		 * 3) Next character not a null, continue to check.
+		 */
+		if (s[0] == '\0') {
+			if (len == 1)
+				return 1;
+			if (s[1] == '\0')
+				return 0;
+		}
+		s++;
+		len--;
+	}
+
+	/* Not the null termination, or not done yet: not printable */
+	if (*s != '\0' || (len != 0))
+		return 0;
+
+	return 1;
+}
+
+/**
+ * Print value of FDT property.
+ *
+ * @param data Pointer to FDT property.
+ * @param len Length of property.
+ */
+static void __print_prop_value(const void *data, int len)
+{
+	if (len == 0)
+		return;
+
+	dbg(" = ");
+
+	/* heavily inspired by u-boot's fdt print */
+	if (__is_string(data, len)) {
+		dbg("\"");
+		int i = 0;
+		while (i < len) {
+			if (i > 0)
+				dbg("\", \"");
+
+			dbg("%s", (const char *)data);
+			i += strlen(data) + 1;
+			data += strlen(data) + 1;
+		}
+		dbg("\"");
+
+	} else if ((len % 4) == 0) {
+		const int32_t *p = (const int32_t *)data;
+		dbg("<");
+		for (int i = 0; i < len / 4; ++i)
+			dbg("%#08x%s", (unsigned int)fdt32_to_cpu(p[i]),
+			    i < (len / 4 - 1) ? " " : "");
+
+		dbg(">");
+	} else {
+		const int32_t *p = (const int32_t *)data;
+		dbg("[");
+		for (int i = 0; i < len / 4; ++i)
+			dbg("%#02x%s", (unsigned int)fdt32_to_cpu(p[i]),
+			    i < (len / 4 - 1) ? " " : "");
+
+		dbg("]");
+	}
+}
+
+void __dbg_fdt(const void *fdt, int node_offset, int depth)
+{
+	int node = 0;
+	fdt_for_each_subnode(node, fdt, node_offset)
+	{
+		__print_char('\t', depth);
+		dbg("%s: {\n", fdt_get_name(fdt, node, 0));
+
+		int property = 0;
+		fdt_for_each_property_offset(property, fdt, node)
+		{
+			int len = 0;
+			const char *name = 0;
+			const void *data = fdt_getprop_by_offset(fdt, property,
+			                                         &name, &len);
+
+			__print_char('\t', depth + 1);
+			dbg("%s", name);
+
+			__print_prop_value(data, len);
+			dbg(";\n");
+		}
+
+		__dbg_fdt(fdt, node, depth + 1);
+
+		__print_char('\t', depth);
+		dbg("};\n\n");
+	}
+}
+#endif
-- 
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