1 files changed, 85 insertions, 0 deletions
diff --git a/src/io/io_helpers.cpp b/src/io/io_helpers.cpp
new file mode 100644
index 0000000..c2cf2be
--- /dev/null
+++ b/src/io/io_helpers.cpp
@@ -0,0 +1,85 @@
+#include "io_helpers.h"
+
+#include "io.h"
+
+#include <cassert>
+
+namespace saw {
+void read_task_and_step_helper::read_step(input_stream &reader) {
+	while (read_task.has_value()) {
+		read_io_task &task = *read_task;
+
+		error_or<size_t> n_err = reader.read(task.buffer, task.max_length);
+		if (n_err.is_error()) {
+			const error &error = n_err.get_error();
+			if (error.is_critical()) {
+				if (read_done) {
+					read_done->fail(error.copy_error());
+				}
+				read_task = std::nullopt;
+			}
+
+			break;
+		} else if (n_err.is_value()) {
+			size_t n = n_err.get_value();
+			if (static_cast<size_t>(n) >= task.min_length &&
+				static_cast<size_t>(n) <= task.max_length) {
+				if (read_done) {
+					read_done->feed(n + task.already_read);
+				}
+				read_task = std::nullopt;
+			} else {
+				task.buffer = static_cast<uint8_t *>(task.buffer) + n;
+				task.min_length -= static_cast<size_t>(n);
+				task.max_length -= static_cast<size_t>(n);
+				task.already_read += n;
+			}
+
+		} else {
+			if (read_done) {
+				read_done->fail(make_error<err::invalid_state>("Read failed"));
+			}
+			read_task = std::nullopt;
+		}
+	}
+}
+
+void write_task_and_step_helper::write_step(output_stream &writer) {
+	while (write_task.has_value()) {
+		write_io_task &task = *write_task;
+
+		error_or<size_t> n_err = writer.write(task.buffer, task.length);
+
+		if (n_err.is_value()) {
+
+			size_t n = n_err.get_value();
+			assert(n <= task.length);
+			if (n == task.length) {
+				if (write_done) {
+					write_done->feed(n + task.already_written);
+				}
+				write_task = std::nullopt;
+			} else {
+				task.buffer = static_cast<const uint8_t *>(task.buffer) + n;
+				task.length -= n;
+				task.already_written += n;
+			}
+		} else if (n_err.is_error()) {
+			const error &error = n_err.get_error();
+			if (error.is_critical()) {
+				if (write_done) {
+					write_done->fail(error.copy_error());
+				}
+				write_task = std::nullopt;
+			}
+			break;
+		} else {
+			if (write_done) {
+				write_done->fail(make_error<err::invalid_state>("Write failed"));
+			}
+			write_task = std::nullopt;
+		}
+	}
+}
+
+} // namespace saw