From b5452bc9bc09e66121aae35adbd5c504a3f90466 Mon Sep 17 00:00:00 2001
From: Vegard Storheil Eriksen <zyp@jvnv.net>
Date: Thu, 6 Jan 2011 02:12:25 +0100
Subject: Let decoders read a dynamic amount through a Source object.

---
 decoder.h                   | 26 ++++++++++++++++++++------
 decoders/mpg123_decoder.cpp |  9 +++++++--
 decoders/mpg123_decoder.h   |  2 +-
 3 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/decoder.h b/decoder.h
index 9faabc1..31986f7 100644
--- a/decoder.h
+++ b/decoder.h
@@ -7,12 +7,29 @@
 
 #include <string>
 
+class Source {
+	public:
+		virtual std::streamsize read(char* buf, std::streamsize buf_size) = 0;
+};
+
+template<class T>
+class StreamSource : public Source {
+	private:
+		T& s;
+	
+	public:
+		StreamSource(T& s_) : s(s_) {}
+		std::streamsize read(char* buf, std::streamsize buf_size) {
+			return boost::iostreams::read(s, buf, buf_size);
+		}
+};
+
 class DecoderBase {
 	public:
 		typedef boost::shared_ptr<DecoderBase> p;
-		virtual size_t decode(const uint8_t *input, size_t input_size, uint8_t *output, size_t output_size) = 0;
 		virtual ~DecoderBase() {}
 		
+		virtual size_t decode(Source& input, uint8_t *output, size_t output_size) = 0;
 };
 
 //! Input filter to hold a decoder in a filter chain.
@@ -26,11 +43,8 @@ class DecoderFilter : public boost::iostreams::multichar_input_filter {
 		
 		template<typename Source>
 		std::streamsize read(Source& src, char *s, std::streamsize n) {
-			char src_data[0x2000];
-			std::streamsize src_read = boost::iostreams::read(src, src_data, 0x2000);
-			if(src_read < 0)
-				src_read = 0;
-			return decoder->decode((const uint8_t*)src_data, src_read, (uint8_t*)s, n);
+			StreamSource<Source> src_f(src);
+			return decoder->decode(src_f, (uint8_t*)s, n);
 		}
 };
 
diff --git a/decoders/mpg123_decoder.cpp b/decoders/mpg123_decoder.cpp
index 0c2629f..a195c58 100644
--- a/decoders/mpg123_decoder.cpp
+++ b/decoders/mpg123_decoder.cpp
@@ -26,8 +26,13 @@ DecoderMpg123::~DecoderMpg123() {
 	mpg123_delete(handle);
 }
 
-size_t DecoderMpg123::decode(const uint8_t *input, size_t input_size, uint8_t *output, size_t output_size) {
-	if(mpg123_feed(handle, input, input_size) != MPG123_OK) {
+size_t DecoderMpg123::decode(Source& input, uint8_t *output, size_t output_size) {
+	char src_data[0x2000];
+	std::streamsize src_read = input.read(src_data, 0x2000);
+	if(src_read < 0)
+		src_read = 0;
+	
+	if(mpg123_feed(handle, (uint8_t*)src_data, src_read) != MPG123_OK) {
 		throw std::runtime_error(mpg123_strerror(handle));
 	}
 
diff --git a/decoders/mpg123_decoder.h b/decoders/mpg123_decoder.h
index 46f9e4c..9e2bcdf 100644
--- a/decoders/mpg123_decoder.h
+++ b/decoders/mpg123_decoder.h
@@ -12,7 +12,7 @@ class DecoderMpg123 : public DecoderBase {
 	public:
 		DecoderMpg123();
 		~DecoderMpg123();
-		size_t decode(const uint8_t *input, size_t input_size, uint8_t *output, size_t output_size);
+		size_t decode(Source& input, uint8_t *output, size_t output_size);
 };
 
 #endif
-- 
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