Add `unsafe?` option for image creation procedures

- Add (private bitwise) module and use it
- Add (private checker) module and use it
- Add (private double-byte) module and use it

1 files changed, 38 insertions, 0 deletions

diff --git a/pnm/private/bitwise.scm b/pnm/private/bitwise.scm
new file mode 100644
index 0000000..a2f2f74
--- /dev/null
+++ b/pnm/private/bitwise.scm
@@ -0,0 +1,38 @@
+;;; R7RS-PNM --- Library for reading and writing PNM (Portable Any Map) files for R7RS
+;;; Copyright © 2024 Masaya Tojo <masaya@tojo.tokyo>
+;;;
+;;; This file is part of R7RS-PNM.
+;;;
+;;; R7RS-PNM is free software: you can redistribute it and/or modify it
+;;; under the terms of the GNU Lesser General Public License as published
+;;; by the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; R7RS-PNM is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+;;; GNU Lesser General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU Lesser General Public License
+;;; along with R7RS-PNM. If not, see <https://www.gnu.org/licenses/>.
+
+(define-library (pnm private bitwise)
+  (export bitwise-and
+          bitwise-ior
+          arithmetic-shift
+          bit-set?
+          copy-bit)
+  (import (scheme base))
+  (cond-expand
+    ((library (scheme bitwise))
+     (import (only (scheme bitwise)
+                   bitwise-and bitwise-ior arithmetic-shift
+                   bit-set? copy-bit)))
+    ((library (srfi 60))
+     (import (only (srfi 60)
+                   bitwise-and bitwise-ior arithmetic-shift
+                   bit-set? copy-bit)))
+    ((library (srfi 151))
+     (import (only (srfi 151)
+                   bitwise-and bitwise-ior arithmetic-shift
+                   bit-set? copy-bit)))))