Add gemv masked to JIT plus some fixes (#1310)

* add gemv masked to JIT plus some fixes

* some cleanup

* add utils

* fix

* fix 2

* more cleaning

* fix

* remove unused mps matmul support

* one more nit

* revert

mlx/io/load.cpp

@@ -26,6 +26,80 @@ constexpr uint8_t MAGIC[] = {
     0x59,
 };
 
+inline bool is_big_endian() {
+  union ByteOrder {
+    int32_t i;
+    uint8_t c[4];
+  };
+  ByteOrder b = {0x01234567};
+
+  return b.c[0] == 0x01;
+}
+
+// Array protocol typestring for Dtype
+std::string dtype_to_array_protocol(const Dtype& t) {
+  std::ostringstream r;
+  if (size_of(t) > 1) {
+    r << (is_big_endian() ? ">" : "<");
+  } else {
+    r << "|";
+  }
+  r << kindof(t) << (int)size_of(t);
+  return r.str();
+}
+
+// Dtype from array protocol type string
+Dtype dtype_from_array_protocol(std::string_view t) {
+  if (t.length() == 2 || t.length() == 3) {
+    std::string_view r = t.length() == 3 ? t.substr(1, 2) : t;
+
+    if (r == "V2") {
+      return bfloat16;
+    }
+
+    uint8_t size = r[1] - '0';
+
+    switch (r[0]) {
+      case 'b': {
+        if (size == 1)
+          return bool_;
+      }
+      case 'i': {
+        if (size == 1)
+          return int8;
+        else if (size == 2)
+          return int16;
+        else if (size == 4)
+          return int32;
+        else if (size == 8)
+          return int64;
+      }
+      case 'u': {
+        if (size == 1)
+          return uint8;
+        else if (size == 2)
+          return uint16;
+        else if (size == 4)
+          return uint32;
+        else if (size == 8)
+          return uint64;
+      }
+      case 'f': {
+        if (size == 2)
+          return float16;
+        else if (size == 4)
+          return float32;
+      }
+      case 'c': {
+        return complex64;
+      }
+    }
+  }
+
+  throw std::invalid_argument(
+      "[from_str] Invalid array protocol type-string: " + std::string(t));
+}
+
 } // namespace
 
 /** Save array to out stream in .npy format */