diff --git a/faiss/cppcontrib/detail/UintReader.h b/faiss/cppcontrib/detail/UintReader.h
index 81e600f410..fbc7e4db40 100644
--- a/faiss/cppcontrib/detail/UintReader.h
+++ b/faiss/cppcontrib/detail/UintReader.h
@@ -9,6 +9,17 @@
 
 #include <cstdint>
 
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+
+#define Swap2Bytes(val) ((((val) >> 8) & 0x00FF) | (((val) << 8) & 0xFF00))
+
+#define Swap4Bytes(val)                                           \
+    ((((val) >> 24) & 0x000000FF) | (((val) >> 8) & 0x0000FF00) | \
+     (((val) << 8) & 0x00FF0000) | (((val) << 24) & 0xFF000000))
+
+#endif
+
 namespace faiss {
 namespace cppcontrib {
 namespace detail {
@@ -31,7 +42,12 @@ struct Uint8Reader {
                 if (N_ELEMENTS > CPOS + 3) {
                     const uint32_t code32 = *reinterpret_cast<const uint32_t*>(
                             codes + ELEMENT_TO_READ * 4);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    return (code32) >> 24;
+#else
                     return (code32 & 0x000000FF);
+#endif
                 } else {
                     return codes[CPOS];
                 }
@@ -40,7 +56,12 @@ struct Uint8Reader {
                 if (N_ELEMENTS > CPOS + 2) {
                     const uint32_t code32 = *reinterpret_cast<const uint32_t*>(
                             codes + ELEMENT_TO_READ * 4);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    return (code32 & 0x00FF0000) >> 16;
+#else
                     return (code32 & 0x0000FF00) >> 8;
+#endif
                 } else {
                     return codes[CPOS];
                 }
@@ -49,7 +70,12 @@ struct Uint8Reader {
                 if (N_ELEMENTS > CPOS + 1) {
                     const uint32_t code32 = *reinterpret_cast<const uint32_t*>(
                             codes + ELEMENT_TO_READ * 4);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    return (code32 & 0x0000FF00) >> 8;
+#else
                     return (code32 & 0x00FF0000) >> 16;
+#endif
                 } else {
                     return codes[CPOS];
                 }
@@ -58,7 +84,12 @@ struct Uint8Reader {
                 if (N_ELEMENTS > CPOS) {
                     const uint32_t code32 = *reinterpret_cast<const uint32_t*>(
                             codes + ELEMENT_TO_READ * 4);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    return (code32 & 0x000000FF);
+#else
                     return (code32) >> 24;
+#endif
                 } else {
                     return codes[CPOS];
                 }
@@ -87,40 +118,68 @@ struct Uint10Reader {
         switch (SUB_ELEMENT) {
             case 0: {
                 if (N_ELEMENTS > CPOS + 2) {
-                    const uint32_t code32 = *reinterpret_cast<const uint32_t*>(
+                    uint32_t code32 = *reinterpret_cast<const uint32_t*>(
                             codes + ELEMENT_TO_READ * 5);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    code32 = Swap4Bytes(code32);
+#endif
                     return (code32 & 0b0000001111111111);
                 } else {
-                    const uint16_t code16 = *reinterpret_cast<const uint16_t*>(
+                    uint16_t code16 = *reinterpret_cast<const uint16_t*>(
                             codes + ELEMENT_TO_READ * 5 + 0);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    code16 = Swap2Bytes(code16);
+#endif
                     return (code16 & 0b0000001111111111);
                 }
             }
             case 1: {
                 if (N_ELEMENTS > CPOS + 1) {
-                    const uint32_t code32 = *reinterpret_cast<const uint32_t*>(
+                    uint32_t code32 = *reinterpret_cast<const uint32_t*>(
                             codes + ELEMENT_TO_READ * 5);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    code32 = Swap4Bytes(code32);
+#endif
                     return (code32 & 0b000011111111110000000000) >> 10;
                 } else {
-                    const uint16_t code16 = *reinterpret_cast<const uint16_t*>(
+                    uint16_t code16 = *reinterpret_cast<const uint16_t*>(
                             codes + ELEMENT_TO_READ * 5 + 1);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    code16 = Swap2Bytes(code16);
+#endif
                     return (code16 & 0b0000111111111100) >> 2;
                 }
             }
             case 2: {
                 if (N_ELEMENTS > CPOS) {
-                    const uint32_t code32 = *reinterpret_cast<const uint32_t*>(
+                    uint32_t code32 = *reinterpret_cast<const uint32_t*>(
                             codes + ELEMENT_TO_READ * 5);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    code32 = Swap4Bytes(code32);
+#endif
                     return (code32 & 0b00111111111100000000000000000000) >> 20;
                 } else {
-                    const uint16_t code16 = *reinterpret_cast<const uint16_t*>(
+                    uint16_t code16 = *reinterpret_cast<const uint16_t*>(
                             codes + ELEMENT_TO_READ * 5 + 2);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    code16 = Swap2Bytes(code16);
+#endif
                     return (code16 & 0b0011111111110000) >> 4;
                 }
             }
             case 3: {
-                const uint16_t code16 = *reinterpret_cast<const uint16_t*>(
+                uint16_t code16 = *reinterpret_cast<const uint16_t*>(
                         codes + ELEMENT_TO_READ * 5 + 3);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                code16 = Swap2Bytes(code16);
+#endif
                 return (code16 & 0b1111111111000000) >> 6;
             }
         }
@@ -147,45 +206,77 @@ struct Uint12Reader {
         switch (SUB_ELEMENT) {
             case 0: {
                 if (N_ELEMENTS > CPOS + 2) {
-                    const uint32_t code32 = *reinterpret_cast<const uint32_t*>(
+                    uint32_t code32 = *reinterpret_cast<const uint32_t*>(
                             codes + ELEMENT_TO_READ * 6);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    code32 = Swap4Bytes(code32);
+#endif
                     return (code32 & 0b0000111111111111);
                 } else {
-                    const uint16_t code16 = *reinterpret_cast<const uint16_t*>(
+                    uint16_t code16 = *reinterpret_cast<const uint16_t*>(
                             codes + ELEMENT_TO_READ * 6 + 0);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    code16 = Swap2Bytes(code16);
+#endif
                     return (code16 & 0b0000111111111111);
                 }
             }
             case 1: {
                 if (N_ELEMENTS > CPOS + 1) {
-                    const uint32_t code32 = *reinterpret_cast<const uint32_t*>(
+                    uint32_t code32 = *reinterpret_cast<const uint32_t*>(
                             codes + ELEMENT_TO_READ * 6);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    code32 = Swap4Bytes(code32);
+#endif
                     return (code32 & 0b111111111111000000000000) >> 12;
                 } else {
-                    const uint16_t code16 = *reinterpret_cast<const uint16_t*>(
+                    uint16_t code16 = *reinterpret_cast<const uint16_t*>(
                             codes + ELEMENT_TO_READ * 6 + 1);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    code16 = Swap2Bytes(code16);
+#endif
                     return (code16 & 0b1111111111110000) >> 4;
                 }
             }
             case 2: {
                 if (N_ELEMENTS > CPOS + 1) {
-                    const uint32_t code32 = *reinterpret_cast<const uint32_t*>(
+                    uint32_t code32 = *reinterpret_cast<const uint32_t*>(
                             codes + ELEMENT_TO_READ * 6 + 2);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    code32 = Swap4Bytes(code32);
+#endif
                     return (code32 & 0b000011111111111100000000) >> 8;
                 } else {
-                    const uint16_t code16 = *reinterpret_cast<const uint16_t*>(
+                    uint16_t code16 = *reinterpret_cast<const uint16_t*>(
                             codes + ELEMENT_TO_READ * 6 + 3);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    code16 = Swap2Bytes(code16);
+#endif
                     return (code16 & 0b0000111111111111);
                 }
             }
             case 3: {
                 if (N_ELEMENTS > CPOS) {
-                    const uint32_t code32 = *reinterpret_cast<const uint32_t*>(
+                    uint32_t code32 = *reinterpret_cast<const uint32_t*>(
                             codes + ELEMENT_TO_READ * 6 + 2);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    code32 = Swap4Bytes(code32);
+#endif
                     return (code32 & 0b11111111111100000000000000000000) >> 20;
                 } else {
-                    const uint16_t code16 = *reinterpret_cast<const uint16_t*>(
+                    uint16_t code16 = *reinterpret_cast<const uint16_t*>(
                             codes + ELEMENT_TO_READ * 6 + 4);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    code16 = Swap2Bytes(code16);
+#endif
                     return (code16 & 0b1111111111110000) >> 4;
                 }
             }
@@ -208,23 +299,43 @@ struct Uint16Reader {
         switch (SUB_ELEMENT) {
             case 0: {
                 if (N_ELEMENTS > CPOS + 1) {
-                    const uint32_t code32 = *reinterpret_cast<const uint32_t*>(
+                    uint32_t code32 = *reinterpret_cast<const uint32_t*>(
                             codes + ELEMENT_TO_READ * 4);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    code32 = Swap4Bytes(code32);
+#endif
                     return (code32 & 0x0000FFFF);
                 } else {
                     const uint16_t* const __restrict codesFp16 =
                             reinterpret_cast<const uint16_t*>(codes);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    uint16_t rt = codesFp16[CPOS];
+                    rt = Swap2Bytes(rt);
+                    return rt;
+#endif
                     return codesFp16[CPOS];
                 }
             }
             case 1: {
                 if (N_ELEMENTS > CPOS) {
-                    const uint32_t code32 = *reinterpret_cast<const uint32_t*>(
+                    uint32_t code32 = *reinterpret_cast<const uint32_t*>(
                             codes + ELEMENT_TO_READ * 4);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    code32 = Swap4Bytes(code32);
+#endif
                     return code32 >> 16;
                 } else {
                     const uint16_t* const __restrict codesFp16 =
                             reinterpret_cast<const uint16_t*>(codes);
+#if !defined(_MSC_VER) && \
+        (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+                    uint16_t rt = codesFp16[CPOS];
+                    rt = Swap2Bytes(rt);
+                    return rt;
+#endif
                     return codesFp16[CPOS];
                 }
             }