lib: accessor to get contents of a memory-mapped file as bytes

MemoryMappedFile's data() method returns a void* as it has no idea what
type the contents are.  Viewing it as bytes is a very common operation
so add a convience method that wraps the pointer in a Span<uint8_t>.

Signed-off-by: Rick Altherr <kc8apf@kc8apf.net>

lib/include/prjxray/memory_mapped_file.h

@@ -4,6 +4,8 @@
 #include <memory>
 #include <string>
 
+#include <absl/types/span.h>
+
 namespace prjxray {
 
 class MemoryMappedFile {
@@ -16,6 +18,10 @@ class MemoryMappedFile {
 	void* const data() const { return data_; }
 	const size_t size() const { return size_; }
 
+	absl::Span<uint8_t> as_bytes() const {
+		return {static_cast<uint8_t*>(data_), size_};
+	}
+
  private:
 	MemoryMappedFile(void *data, size_t size)
 		: data_(data), size_(size) {};

lib/include/prjxray/xilinx/xc7series/bitstream_reader.h

@@ -47,7 +47,7 @@ class BitstreamReader {
 	// Construct a `BitstreamReader` from a Container of bytes.
 	// Any bytes preceding an initial sync word are ignored.
 	template<typename T>
-	static absl::optional<BitstreamReader> InitWithBytes(T &bitstream);
+	static absl::optional<BitstreamReader> InitWithBytes(T bitstream);
 
 	const std::vector<uint32_t> &words() { return words_; };
 
@@ -62,7 +62,7 @@ class BitstreamReader {
 };
 
 template<typename T>
-absl::optional<BitstreamReader> BitstreamReader::InitWithBytes(T &bitstream) {
+absl::optional<BitstreamReader> BitstreamReader::InitWithBytes(T bitstream) {
 	// If this is really a Xilinx 7-Series bitstream, there will be a sync
 	// word somewhere toward the beginning.
 	auto sync_pos = std::search(bitstream.begin(), bitstream.end(),

tools/bitread.cc

@@ -78,10 +78,8 @@ int main(int argc, char **argv) {
 		std::cout << "Bitstream size: " << in_file->size() << " bytes"
 	    		  << std::endl;
 
-		auto in_bytes = absl::Span<uint8_t>(
-				static_cast<uint8_t*>(in_file->data()),
-				in_file->size());
-		reader = xc7series::BitstreamReader::InitWithBytes(in_bytes);
+		reader = xc7series::BitstreamReader::InitWithBytes(
+				in_file->as_bytes());
 	} else {
 		std::vector<uint8_t> bitdata;
 		while (1) {

tools/bittool.cc

@@ -31,10 +31,8 @@ int ListConfigPackets(int argc, char *argv[]) {
 		return 1;
 	}
 
-	auto in_bytes = absl::Span<uint8_t>(
-			static_cast<uint8_t*>(in_file->data()),
-			in_file->size());
-	auto reader = xc7series::BitstreamReader::InitWithBytes(in_bytes);
+	auto reader = xc7series::BitstreamReader::InitWithBytes(
+			in_file->as_bytes());
 	if (!reader) {
 		std::cerr << "Input doesn't look like a bitstream"
 			  << std::endl;

tools/gen_part_base_yaml.cc

@@ -31,10 +31,8 @@ int main(int argc, char *argv[]) {
 		return 1;
 	}
 
-	auto in_bytes = absl::Span<uint8_t>(
-			static_cast<uint8_t*>(in_file->data()),
-			in_file->size());
-	auto reader = xc7series::BitstreamReader::InitWithBytes(in_bytes);
+	auto reader = xc7series::BitstreamReader::InitWithBytes(
+			in_file->as_bytes());
 	if (!reader) {
 		std::cerr << "Input doesn't look like a bitstream"
 			  << std::endl;