added frombuffer array initialisation function

Author: v923z

code/ulab.c

@@ -162,6 +162,10 @@ STATIC const mp_map_elem_t ulab_globals_table[] = {
             { MP_ROM_QSTR(MP_QSTR_eye), (mp_obj_t)&create_eye_obj },
         #endif
     #endif /* ULAB_MAX_DIMS */
+    // frombuffer adds 600 bytes to the firmware
+    #if ULAB_CREATE_HAS_FROMBUFFER
+        { MP_ROM_QSTR(MP_QSTR_frombuffer), (mp_obj_t)&create_frombuffer_obj },
+    #endif
     #if ULAB_CREATE_HAS_FULL
         { MP_ROM_QSTR(MP_QSTR_full), (mp_obj_t)&create_full_obj },
     #endif

code/ulab.h

@@ -148,6 +148,7 @@
 #define ULAB_CREATE_HAS_CONCATENATE     (1)
 #define ULAB_CREATE_HAS_DIAG            (1)
 #define ULAB_CREATE_HAS_EYE             (1)
+#define ULAB_CREATE_HAS_FROMBUFFER      (1)
 #define ULAB_CREATE_HAS_FULL            (1)
 #define ULAB_CREATE_HAS_LINSPACE        (1)
 #define ULAB_CREATE_HAS_LOGSPACE        (1)

code/ulab_create.c

@@ -630,3 +630,51 @@ mp_obj_t create_zeros(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args
 
 MP_DEFINE_CONST_FUN_OBJ_KW(create_zeros_obj, 0, create_zeros);
 #endif
+
+#if ULAB_CREATE_HAS_FROMBUFFER
+mp_obj_t create_frombuffer(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_, MP_ARG_REQUIRED | MP_ARG_OBJ, { .u_rom_obj = mp_const_none } },
+        { MP_QSTR_dtype, MP_ARG_KW_ONLY | MP_ARG_OBJ, { .u_rom_obj = MP_ROM_INT(NDARRAY_FLOAT) } },
+        { MP_QSTR_count, MP_ARG_KW_ONLY | MP_ARG_OBJ, { .u_rom_obj = MP_ROM_INT(-1) } },
+        { MP_QSTR_offset, MP_ARG_KW_ONLY | MP_ARG_OBJ, { .u_rom_obj = MP_ROM_INT(0) } },
+    };
+
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    uint8_t dtype = mp_obj_get_int(args[1].u_obj);
+    size_t offset = mp_obj_get_int(args[3].u_obj);
+
+    mp_buffer_info_t bufinfo;
+    if(mp_get_buffer(args[0].u_obj, &bufinfo, MP_BUFFER_READ)) {
+        size_t sz = 1;
+        if(dtype != NDARRAY_BOOL) { // mp_binary_get_size doesn't work with Booleans
+            sz = mp_binary_get_size('@', dtype, NULL);
+        }
+        if(bufinfo.len < offset) {
+            mp_raise_ValueError(translate("offset must be non-negative and no greater than buffer length"));
+        }
+        size_t len = (bufinfo.len - offset) / sz;
+        if((len * sz) != (bufinfo.len - offset)) {
+            mp_raise_ValueError(translate("buffer size must be a multiple of element size"));
+        }
+        if(mp_obj_get_int(args[2].u_obj) > 0) {
+            size_t count = mp_obj_get_int(args[2].u_obj);
+            if(len < count) {
+                mp_raise_ValueError(translate("buffer is smaller than requested size"));
+            } else {
+                len -= count;
+            }
+        }
+        ndarray_obj_t *ndarray = ndarray_new_linear_array(len, dtype);
+        uint8_t *array = (uint8_t *)ndarray->array;
+        uint8_t *buffer = bufinfo.buf;
+        memcpy(array, buffer + offset, len * sz);
+        return MP_OBJ_FROM_PTR(ndarray);
+    }
+    return mp_const_none;
+}
+
+MP_DEFINE_CONST_FUN_OBJ_KW(create_frombuffer_obj, 1, create_frombuffer);
+#endif

code/ulab_create.h

@@ -62,4 +62,10 @@ mp_obj_t create_zeros(size_t , const mp_obj_t *, mp_map_t *);
 MP_DECLARE_CONST_FUN_OBJ_KW(create_zeros_obj);
 #endif
 
+
+#if ULAB_CREATE_HAS_FROMBUFFER
+mp_obj_t create_frombuffer(size_t , const mp_obj_t *, mp_map_t *);
+MP_DECLARE_CONST_FUN_OBJ_KW(create_frombuffer_obj);
+#endif
+
 #endif

docs/ulab-change-log.md

@@ -1,5 +1,11 @@
 Thu, 14 Jan 2021
 
+version 1.7.0
+
+    added frombuffer
+
+Thu, 14 Jan 2021
+
 version 1.6.2
 
     fix indexing issue in diff