From 02954c2ec665809b8cc7e333e32fd710e04e613e Mon Sep 17 00:00:00 2001
From: lloyd <lloyd@randombit.net>
Date: Sun, 27 Dec 2009 00:55:44 +0000
Subject: Add a generalized Buffered_Operation. Relies on tr1 for sane
 callbacks (std::tr1::function).

---
 src/utils/buf_op/buf_op.cpp | 120 ++++++++++++++++++++++++++++++++++++++++++++
 src/utils/buf_op/buf_op.h   |  45 +++++++++++++++++
 src/utils/buf_op/info.txt   |  11 ++++
 3 files changed, 176 insertions(+)
 create mode 100644 src/utils/buf_op/buf_op.cpp
 create mode 100644 src/utils/buf_op/buf_op.h
 create mode 100644 src/utils/buf_op/info.txt

diff --git a/src/utils/buf_op/buf_op.cpp b/src/utils/buf_op/buf_op.cpp
new file mode 100644
index 000000000..2b5b943cd
--- /dev/null
+++ b/src/utils/buf_op/buf_op.cpp
@@ -0,0 +1,120 @@
+/**
+* Buffering Central
+* (C) 2009 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/buf_op.h>
+#include <botan/mem_ops.h>
+#include <botan/internal/rounding.h>
+#include <stdexcept>
+
+#include <stdio.h>
+#include <assert.h>
+
+namespace Botan {
+
+namespace {
+
+const size_t BUFFER_MULTIPLE = 2;
+
+//static_assert(BUFFER_MULTIPLE >= 2, "BUFFER_MULTIPLE must be >= 2");
+
+}
+
+Buffered_Operation::Buffered_Operation(callback_fn m_fn,
+                                       callback_fn f_fn,
+                                       size_t buf_mod,
+                                       size_t final_minimum) :
+   main_fn(m_fn), final_fn(f_fn),
+   final_minimum(final_minimum), main_block_mod(buf_mod),
+   buffer(BUFFER_MULTIPLE * buf_mod), buffer_pos(0)
+   {
+   if(buf_mod == 0)
+      throw std::invalid_argument("buf_mod == 0");
+
+   if(final_minimum > buf_mod)
+      throw std::invalid_argument("final_minimum > buf_mod");
+   }
+
+void Buffered_Operation::reset()
+   {
+   clear_mem(&buffer[0], buffer.size());
+   buffer_pos = 0;
+   }
+
+void Buffered_Operation::write(const byte input[],
+                               size_t input_size)
+   {
+   if(!input_size)
+      return;
+
+   if(buffer_pos + input_size >= main_block_mod + final_minimum)
+      {
+      size_t to_copy = std::min(buffer.size() - buffer_pos, input_size);
+
+      copy_mem(&buffer[buffer_pos], input, to_copy);
+      buffer_pos += to_copy;
+
+      input += to_copy;
+      input_size -= to_copy;
+
+      if(input_size >= final_minimum)
+         {
+         size_t to_proc = round_down(buffer_pos, main_block_mod);
+         main_fn(&buffer[0], to_proc);
+
+         buffer_pos -= to_proc;
+
+         copy_mem(&buffer[0], &buffer[to_proc], buffer_pos);
+         }
+      }
+
+   if(input_size >= final_minimum)
+      {
+      size_t full_blocks = (input_size - final_minimum) / buffer.size();
+      size_t to_copy = full_blocks * buffer.size();
+
+      if(to_copy)
+         {
+         main_fn(input, to_copy);
+
+         input += to_copy;
+         input_size -= to_copy;
+         }
+      }
+
+   assert(input_size + buffer_pos <= buffer.size());
+
+   copy_mem(&buffer[buffer_pos], input, input_size);
+   buffer_pos += input_size;
+   }
+
+void Buffered_Operation::final()
+   {
+   assert(buffer_pos >= final_minimum);
+
+   if(buffer_pos < final_minimum)
+      throw std::runtime_error("Buffered_Operation::final - not enough input");
+
+   size_t spare_blocks = (buffer_pos - final_minimum) / main_block_mod;
+
+   if(spare_blocks)
+      {
+      size_t spare_bytes = main_block_mod * spare_blocks;
+
+      assert(spare_bytes <= buffer_pos);
+
+      main_fn(&buffer[0], spare_bytes);
+
+      assert(buffer_pos - spare_bytes >= final_minimum);
+      final_fn(&buffer[spare_bytes], buffer_pos - spare_bytes);
+      }
+   else
+      {
+      final_fn(&buffer[0], buffer_pos);
+      }
+   }
+
+}
diff --git a/src/utils/buf_op/buf_op.h b/src/utils/buf_op/buf_op.h
new file mode 100644
index 000000000..cc864c47d
--- /dev/null
+++ b/src/utils/buf_op/buf_op.h
@@ -0,0 +1,45 @@
+/**
+* Buffering Central
+* (C) 2009 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_BUFFERED_OPTION_H__
+#define BOTAN_BUFFERED_OPTION_H__
+
+#include <botan/types.h>
+#include <tr1/functional>
+#include <vector>
+
+namespace Botan {
+
+class BOTAN_DLL Buffered_Operation
+   {
+   public:
+      typedef std::tr1::function<void (const byte[], size_t)> callback_fn;
+
+      void write(const byte input[], size_t input_size);
+
+      void final();
+
+      void reset();
+
+      size_t current_position() const { return buffer_pos; }
+
+      Buffered_Operation(callback_fn main_block,
+                         callback_fn final_block,
+                         size_t main_buf_mod,
+                         size_t final_minimum = 0);
+
+   private:
+      callback_fn main_fn, final_fn;
+      size_t final_minimum, main_block_mod;
+
+      std::vector<byte> buffer;
+      size_t buffer_pos;
+   };
+
+}
+
+#endif
diff --git a/src/utils/buf_op/info.txt b/src/utils/buf_op/info.txt
new file mode 100644
index 000000000..657a1e0c4
--- /dev/null
+++ b/src/utils/buf_op/info.txt
@@ -0,0 +1,11 @@
+define BUFFERED_OPERATION
+
+uses_tr1 yes
+
+<source>
+buf_op.cpp
+</source>
+
+<header:public>
+buf_op.h
+</header:public>
-- 
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