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-rw-r--r--src/lib/util/ioprocsfill.h190
1 files changed, 190 insertions, 0 deletions
diff --git a/src/lib/util/ioprocsfill.h b/src/lib/util/ioprocsfill.h
new file mode 100644
index 00000000000..7179d61852c
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+++ b/src/lib/util/ioprocsfill.h
@@ -0,0 +1,190 @@
+// license:BSD-3-Clause
+// copyright-holders:Vas Crabb
+/***************************************************************************
+
+ ioprocsfill.h
+
+ Wrappers that automatically fill extra space
+
+***************************************************************************/
+#ifndef MAME_LIB_UTIL_IOPROCSFILL_H
+#define MAME_LIB_UTIL_IOPROCSFILL_H
+
+#pragma once
+
+#include <algorithm>
+#include <cassert>
+#include <cstdint>
+#include <system_error>
+
+
+namespace util {
+
+template <std::uint8_t DefaultFiller>
+class fill_wrapper_base
+{
+public:
+ std::uint8_t get_filler() const noexcept
+ {
+ return m_filler;
+ }
+
+ void set_filler(std::uint8_t filler) noexcept
+ {
+ m_filler = filler;
+ }
+
+private:
+ std::uint8_t m_filler = DefaultFiller;
+};
+
+
+template <typename Base, std::uint8_t DefaultFiller = 0U>
+class read_stream_fill_wrapper : public Base, public virtual fill_wrapper_base<DefaultFiller>
+{
+public:
+ using Base::Base;
+
+ virtual std::error_condition read_some(void *buffer, std::size_t length, std::size_t &actual) noexcept override
+ {
+ // not atomic with respect to other read/write calls
+ actual = 0U;
+ std::error_condition err;
+ std::size_t chunk;
+ do
+ {
+ err = Base::read_some(
+ reinterpret_cast<std::uint8_t *>(buffer) + actual,
+ length - actual,
+ chunk);
+ actual += chunk;
+ }
+ while ((length > actual) && ((!err && chunk) || (std::errc::interrupted == err)));
+ assert(length >= actual);
+ std::fill(
+ reinterpret_cast<std::uint8_t *>(buffer) + actual,
+ reinterpret_cast<std::uint8_t *>(buffer) + length,
+ fill_wrapper_base<DefaultFiller>::get_filler());
+ return err;
+ }
+};
+
+
+template <typename Base, std::uint8_t DefaultFiller = 0U>
+class random_read_fill_wrapper : public read_stream_fill_wrapper<Base, DefaultFiller>
+{
+public:
+ using read_stream_fill_wrapper<Base, DefaultFiller>::read_stream_fill_wrapper;
+
+ virtual std::error_condition read_some_at(std::uint64_t offset, void *buffer, std::size_t length, std::size_t &actual) noexcept override
+ {
+ // not atomic with respect to other read/write calls
+ actual = 0U;
+ std::error_condition err;
+ std::size_t chunk;
+ do
+ {
+ err = Base::read_some_at(
+ offset,
+ reinterpret_cast<std::uint8_t *>(buffer) + actual,
+ length - actual,
+ chunk);
+ offset += chunk;
+ actual += chunk;
+ }
+ while ((length > actual) && ((!err && chunk) || (std::errc::interrupted == err)));
+ assert(length >= actual);
+ std::fill(
+ reinterpret_cast<std::uint8_t *>(buffer) + actual,
+ reinterpret_cast<std::uint8_t *>(buffer) + length,
+ fill_wrapper_base<DefaultFiller>::get_filler());
+ return err;
+ }
+};
+
+
+template <typename Base, std::uint8_t DefaultFiller = 0U, std::size_t FillBlock = 1024U>
+class random_write_fill_wrapper : public Base, public virtual fill_wrapper_base<DefaultFiller>
+{
+public:
+ using Base::Base;
+
+ virtual std::error_condition write_some(void const *buffer, std::size_t length, std::size_t &actual) noexcept override
+ {
+ // not atomic with respect to other read/write calls
+ std::error_condition err;
+ actual = 0U;
+
+ std::uint64_t offset;
+ std::uint64_t current;
+ err = Base::tell(offset);
+ if (err)
+ return err;
+ err = Base::length(current);
+ if (err)
+ return err;
+
+ if (current < offset)
+ {
+ std::uint64_t unfilled = offset - current;
+ std::uint8_t fill_buffer[FillBlock];
+ std::fill(
+ fill_buffer,
+ fill_buffer + std::min<std::common_type_t<std::size_t, std::uint64_t> >(FillBlock, unfilled),
+ fill_wrapper_base<DefaultFiller>::get_filler());
+ do
+ {
+ std::size_t const chunk = std::min<std::common_type_t<std::size_t, std::uint64_t> >(FillBlock, unfilled);
+ std::size_t filled;
+ err = Base::write_some_at(current, fill_buffer, chunk, filled);
+ current += filled;
+ unfilled -= filled;
+ if (err && (std::errc::interrupted != err))
+ return err;
+ }
+ while (unfilled);
+ }
+
+ return Base::write_some(buffer, length, actual);
+ }
+
+ virtual std::error_condition write_some_at(std::uint64_t offset, void const *buffer, std::size_t length, std::size_t &actual) noexcept override
+ {
+ // not atomic with respect to other read/write calls
+ std::error_condition err;
+ std::uint64_t current;
+ err = Base::length(current);
+ if (!err && (current < offset))
+ {
+ std::uint64_t unfilled = offset - current;
+ std::uint8_t fill_buffer[FillBlock];
+ std::fill(
+ fill_buffer,
+ fill_buffer + std::min<std::common_type_t<std::size_t, std::uint64_t> >(FillBlock, unfilled),
+ fill_wrapper_base<DefaultFiller>::get_filler());
+ do
+ {
+ std::size_t const chunk = std::min<std::common_type_t<std::size_t, std::uint64_t> >(FillBlock, unfilled);
+ std::size_t filled;
+ err = Base::write_some_at(current, fill_buffer, chunk, filled);
+ current += filled;
+ unfilled -= filled;
+ }
+ while (unfilled && (!err || (std::errc::interrupted == err)));
+ }
+ if (err)
+ {
+ actual = 0U;
+ return err;
+ }
+ return Base::write_some_at(offset, buffer, length, actual);
+ }
+};
+
+
+template <typename Base, std::uint8_t DefaultFiller = 0U, std::size_t FillBlock = 1024U>
+using random_read_write_fill_wrapper = random_write_fill_wrapper<random_read_fill_wrapper<Base, DefaultFiller>, DefaultFiller, FillBlock>;
+
+} // namespace util
+
+#endif // MAME_LIB_UTIL_IOPROCSFILL_H