Support decoding on big endian systems

Author: scaramallion

build.py

@@ -3,6 +3,7 @@
 from pathlib import Path
 import platform
 import shutil
+from struct import unpack
 import subprocess
 import sys
 from typing import Any, List, Dict
@@ -33,9 +34,17 @@ def build(setup_kwargs: Any) -> Any:
         # Skip configuration if running with `sdist`
         if 'sdist' not in sys.argv:
             opts = get_gcc_args()
+            if sys.byteorder == "big":
+                if "-mfpmath=387" in opts["ADDOPTS"]:
+                    opts["ADDOPTS"].remove("-mfpmath=387")
+
             extra_compile_args += opts['ADDOPTS']
             extra_link_args += opts['EXTRA_LIBS']
 
+    macros = [("NPY_NO_DEPRECATED_API", "NPY_1_7_API_VERSION")]
+    if unpack("h", b"\x00\x01")[0] == 1:
+        macros.append(("JPG_BIG_ENDIAN", "1"))
+
     ext = Extension(
         '_libjpeg',
         [os.fspath(p) for p in get_source_files()],
@@ -47,6 +56,7 @@ def build(setup_kwargs: Any) -> Any:
         ],
         extra_compile_args=extra_compile_args,
         extra_link_args=extra_link_args,
+        define_macros=macros,
     )
 
     ext_modules = cythonize(

docs/changes/v2.1.0.rst

@@ -0,0 +1,13 @@
+.. _v2.1.0:
+
+2.1.0
+=====
+
+* Use ``libjpeg`` v1.67
+* Fixed a decoding failure for JPEG 10918 file with an Adobe v101 APP14 marker
+
+2.1.1
+=====
+
+* Updated dependencies to allow NumPy > 2.0
+* Tests updated to use ``pydicom.pixels``

docs/changes/v2.2.0.rst

@@ -0,0 +1,6 @@
+.. _v2.2.0:
+
+2.2.0
+=====
+
+* Support NumPy > 2.0 with Python 3.9+

docs/changes/v2.3.0.rst

@@ -0,0 +1,7 @@
+.. _v2.3.0:
+
+2.3.0
+=====
+
+* Supported Python versions are 3.9 to 3.13
+* Added support for decoding on big endian systems

lib/interface/decode.cpp

@@ -30,11 +30,11 @@ std::string Decode(
     Parameters
     ----------
     char *inArray
-        Pointer to the first element of a numpy.ndarray containing the JPEG
-        data to be decompressed.
+        Pointer to the first element of a bytearray or numpy.ndarray containing the
+        JPEG data to be decompressed.
     char *outArray
-        Pointer to the first element of a numpy.ndarray where the decompressed
-        JPEG data should be written.
+        Pointer to the first element of bytearray or numpy.ndarray where the
+        decompressed JPEG data should be written.
     int inLength
         Length of the input array
     int outLength

lib/interface/streamhook.cpp

@@ -88,7 +88,7 @@ JPG_LONG OStreamHook(struct JPG_Hook *hook, struct JPG_TagItem *tags)
     static ULONG OpenComponents = 0;
     struct StreamMemory *omm  = (struct StreamMemory *)(hook->hk_pData);
     struct StreamData *out = (struct StreamData *)(omm->omm_pTarget);
-    // Pointer to the output numpy array, currently at offset out->position
+    // Pointer to the output bytearray/numpy array, currently at offset out->position
     char *oArray = (char *)(out->pData);
 
     UWORD comp  = tags->GetTagData(JPGTAG_BIO_COMPONENT);
@@ -323,12 +323,26 @@ JPG_LONG OStreamHook(struct JPG_Hook *hook, struct JPG_TagItem *tags)
                             }
                         } else {
                             // DICOM should always be integer input
-                            // Write pixel data to target
+                            // Need to byte swap if on a big endian system
+                            #ifdef JPG_BIG_ENDIAN
+                                ULONG count = width * height * omm->omm_usDepth;
+                                if (omm->omm_ucPixelType == CTYP_UWORD) {
+                                    // ULONG count = width * height * omm->omm_usDepth;
+                                    UWORD *data = (UWORD *)omm->omm_pMemPtr;
+
+                                    do {
+                                        *data = (*data >> 8) | ((*data & 0xff) << 8);
+                                        data++;
+                                    } while(--count);
+                                }
+                            #endif
+
+                            // Write the decoded data to the output
+                            // For each pixel
+                            ULONG count2 = width * height * omm->omm_usDepth;
                             ULONG size = omm->omm_ucPixelType & CTYP_SIZE_MASK;
-                            ULONG count = width * height * omm->omm_usDepth;
                             UBYTE *mem = (UBYTE *)(omm->omm_pMemPtr);
-                            // For each pixel
-                            for (ULONG ii = 1; ii <= count; ii++) {
+                            for (ULONG ii = 1; ii <= count2; ii++) {
                                 // For each byte of the pixel
                                 for (ULONG jj = 1; jj <= size; jj++) {
                                     if (out->position >= out->length) {