From 7199e74aa22e592a3b77bdd81f735edca5470596 Mon Sep 17 00:00:00 2001
From: Benji Dial <benji@benjidial.net>
Date: Sat, 20 Jan 2024 17:59:40 -0500
Subject: update

---
 libraries/euler/cstdio.cpp | 102 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 102 insertions(+)
 create mode 100644 libraries/euler/cstdio.cpp

(limited to 'libraries/euler/cstdio.cpp')

diff --git a/libraries/euler/cstdio.cpp b/libraries/euler/cstdio.cpp
new file mode 100644
index 0000000..367e7e0
--- /dev/null
+++ b/libraries/euler/cstdio.cpp
@@ -0,0 +1,102 @@
+#include <euler/syscall.hpp>
+#include <cassert>
+#include <cstring>
+#include <cstdio>
+
+namespace euler {
+
+  //read-only with no error bits for now
+  struct file_t {
+
+    syscall::file_handle handle;
+
+    //TODO: variable size buffer? maybe a multiple of block size for device?
+    char buffer[1024];
+    //in bytes, aligned to buffer size; 1 for no buffer loaded
+    uint64_t buffer_start;
+
+    bool is_offset_in_buffer() {
+      return
+        buffer_start != 1 && offset >= buffer_start &&
+        offset < buffer_start + 1024;
+    }
+
+    syscall::file_result ensure_offset_in_buffer() {
+      if (is_offset_in_buffer())
+        return syscall::file_result::success;
+      uint64_t new_buffer_start = (offset / 1024) * 1024;
+      uint64_t new_buffer_end = new_buffer_start + 1024;
+      if (length < new_buffer_end)
+        new_buffer_end = length;
+      syscall::file_result result = _syscall_read_from_file(
+        handle, new_buffer_start, new_buffer_end - new_buffer_start, buffer);
+      if (result == syscall::file_result::success)
+        buffer_start = new_buffer_start;
+      return result;
+    }
+
+    uint64_t offset;
+    uint64_t length;
+
+  };
+
+}
+
+namespace std {
+
+  FILE *fopen(const char *path, const char *mode) {
+
+    assert(mode[0] == 'r' && mode[1] == '\0');
+
+    euler::syscall::file_handle handle;
+    euler::syscall::file_result result =
+      _syscall_open_file(path, strlen(path), handle);
+    if (result != euler::syscall::file_result::success)
+      return 0;
+
+    uint64_t length;
+    result = _syscall_get_file_length(handle, length);
+    if (result != euler::syscall::file_result::success) {
+      _syscall_close_file(handle);
+      return 0;
+    }
+
+    return new FILE {
+      .handle = handle,
+      .buffer = {},
+      .buffer_start = 1,
+      .offset = 0,
+      .length = length
+    };
+
+  }
+
+  int fclose(FILE *file) {
+    _syscall_close_file(file->handle);
+    delete file;
+    return 0;
+  }
+
+  int fgetc(FILE *from) {
+    if (from->offset >= from->length)
+      return EOF;
+    assert(
+      from->ensure_offset_in_buffer() == euler::syscall::file_result::success);
+    char ch = from->buffer[from->offset - from->buffer_start];
+    ++from->offset;
+    return ch;
+  }
+
+  int ungetc(int ch, FILE *from) {
+    if (ch == EOF || from->offset == 0)
+      return EOF;
+    --from->offset;
+    if (!from->is_offset_in_buffer()) {
+      ++from->offset;
+      return EOF;
+    }
+    from->buffer[from->offset - from->buffer_start] = ch;
+    return ch;
+  }
+
+}
-- 
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