1 files changed, 59 insertions, 0 deletions
diff --git a/libsyscalls_to_tracer_endian.c b/libsyscalls_to_tracer_endian.c
new file mode 100644
index 0000000..ad3b8a4
--- /dev/null
+++ b/libsyscalls_to_tracer_endian.c
@@ -0,0 +1,59 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+/* XXX be smarter if using the same byteorder */
+enum libsyscalls_error
+libsyscalls_to_tracer_endian(const void *value_in, size_t in_offset,
+                             const struct libsyscalls_datatype_description *type,
+                             unsigned long long int *value_out)
+{
+	const unsigned long long int limit = sizeof(long long int) / sizeof(char) * CHAR_BIT;
+	unsigned long long int bytebits, bytemask, byte, value, remmask, valmask;
+	unsigned long long int offset = in_offset, offset_byte, offset_bit, off;
+	const unsigned char *in = value_in;
+	size_t i;
+
+	if (!type || !value_in || !value_out || (unsigned long long int)type->width_in_bits > limit)
+		return LIBSYSCALLS_E_INVAL;
+
+	bytebits = (unsigned long long int)type->width_in_bits;
+	for (i = 0; !LIBSYSCALLS_IS_BYTEORDER_END_AT(type, i); i++)
+		if (type->byteorder[i] && (unsigned long long int)type->byteorder[i] < bytebits)
+			bytebits = (unsigned long long int)type->byteorder[i];
+
+	if (bytebits > limit)
+		return LIBSYSCALLS_E_INVAL;
+	else if (bytebits == limit)
+		bytemask = ~0ULL;
+	else
+		bytemask = (1ULL << bytebits) - 1ULL;
+
+	if ((unsigned long long int)type->width_in_bits == limit)
+		valmask = ~0ULL;
+	else
+		valmask = (1ULL << (unsigned long long int)type->width_in_bits) - 1ULL;
+
+	value = 0;
+	for (i = 0; !LIBSYSCALLS_IS_BYTEORDER_END_AT(type, i); i++) {
+		offset_byte = offset / CHAR_BIT;
+		offset_bit = offset % CHAR_BIT;
+		offset += bytebits;
+
+		byte = (unsigned long long int)in[offset_byte] >> offset_bit;
+		remmask = bytemask & (valmask >> type->byteorder[i]);
+
+		off = CHAR_BIT - offset_bit;
+		if (remmask >>= off) {
+			do {
+				byte |= (unsigned long long int)in[++offset_byte] << off;
+				off += CHAR_BIT;
+			} while (remmask >>= CHAR_BIT);
+		}
+		byte &= bytemask & (valmask >> type->byteorder[i]);
+		value |= byte << type->byteorder[i];
+	}
+
+	*value_out = value;
+	return LIBSYSCALLS_E_OK;
+}