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py/objarray: Introduce "memview_offset" alias for "free" field of object 

Both mp_type_array and mp_type_memoryview use the same object structure,
mp_obj_array_t, but for the case of memoryview, some fields, e.g. "free",
have different meaning.  As the "free" field is also a bitfield, assume
that (anonymous) union can't be used here (for the concerns of possible
compatibility issues with wide array of toolchains), and just add a field
alias using a #define.  As it's a define, it should be a selective
identifier, so use verbose "memview_offset" to avoid any clashes.
This commit is contained in:
Paul Sokolovsky 2018-09-16 13:41:30 +03:00 committed by Damien George
parent 39eef27083
commit a261d8b615
2 changed files with 18 additions and 8 deletions
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19
py/objarray.c
View File

@ -50,11 +50,14 @@
// Note that we don't handle the case where the original buffer might change
// size due to a resize of the original parent object.
// make (& TYPECODE_MASK) a null operation if memorview not enabled
#if MICROPY_PY_BUILTINS_MEMORYVIEW
#define TYPECODE_MASK (0x7f)
#define memview_offset free
#else
// make (& TYPECODE_MASK) a null operation if memorview not enabled
#define TYPECODE_MASK (~(size_t)0)
// memview_offset should not be accessed if memoryview is not enabled,
// so not defined to catch errors
#endif
STATIC mp_obj_t array_iterator_new(mp_obj_t array_in, mp_obj_iter_buf_t *iter_buf);
@ -200,7 +203,7 @@ mp_obj_t mp_obj_new_memoryview(byte typecode, size_t nitems, void *items) {
mp_obj_array_t *self = m_new_obj(mp_obj_array_t);
self->base.type = &mp_type_memoryview;
self->typecode = typecode;
self->free = 0;
self->memview_offset = 0;
self->len = nitems;
self->items = items;
return MP_OBJ_FROM_PTR(self);
@ -396,7 +399,7 @@ STATIC mp_obj_t array_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value
src_items = src_slice->items;
#if MICROPY_PY_BUILTINS_MEMORYVIEW
if (MP_OBJ_IS_TYPE(value, &mp_type_memoryview)) {
src_items = (uint8_t*)src_items + (src_slice->free * item_sz);
src_items = (uint8_t*)src_items + (src_slice->memview_offset * item_sz);
}
#endif
} else if (MP_OBJ_IS_TYPE(value, &mp_type_bytes)) {
@ -423,7 +426,7 @@ STATIC mp_obj_t array_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value
if (len_adj != 0) {
goto compat_error;
}
dest_items += o->free * item_sz;
dest_items += o->memview_offset * item_sz;
}
#endif
if (len_adj > 0) {
@ -459,7 +462,7 @@ STATIC mp_obj_t array_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value
} else if (o->base.type == &mp_type_memoryview) {
res = m_new_obj(mp_obj_array_t);
*res = *o;
res->free += slice.start;
res->memview_offset += slice.start;
res->len = slice.stop - slice.start;
#endif
} else {
@ -472,7 +475,7 @@ STATIC mp_obj_t array_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value
size_t index = mp_get_index(o->base.type, o->len, index_in, false);
#if MICROPY_PY_BUILTINS_MEMORYVIEW
if (o->base.type == &mp_type_memoryview) {
index += o->free;
index += o->memview_offset;
if (value != MP_OBJ_SENTINEL && !(o->typecode & MP_OBJ_ARRAY_TYPECODE_FLAG_RW)) {
// store to read-only memoryview
return MP_OBJ_NULL;
@ -503,7 +506,7 @@ STATIC mp_int_t array_get_buffer(mp_obj_t o_in, mp_buffer_info_t *bufinfo, mp_ui
// read-only memoryview
return 1;
}
bufinfo->buf = (uint8_t*)bufinfo->buf + (size_t)o->free * sz;
bufinfo->buf = (uint8_t*)bufinfo->buf + (size_t)o->memview_offset * sz;
}
#else
(void)flags;
@ -624,7 +627,7 @@ STATIC mp_obj_t array_iterator_new(mp_obj_t array_in, mp_obj_iter_buf_t *iter_bu
o->cur = 0;
#if MICROPY_PY_BUILTINS_MEMORYVIEW
if (array->base.type == &mp_type_memoryview) {
o->offset = array->free;
o->offset = array->memview_offset;
}
#endif
return MP_OBJ_FROM_PTR(o);

7
py/objarray.h
View File

@ -32,11 +32,18 @@
// Used only for memoryview types, set in "typecode" to indicate a writable memoryview
#define MP_OBJ_ARRAY_TYPECODE_FLAG_RW (0x80)
// This structure is used for all of bytearray, array.array, memoryview
// objects. Note that memoryview has different meaning for some fields,
// see comment at the beginning of objarray.c.
typedef struct _mp_obj_array_t {
mp_obj_base_t base;
size_t typecode : 8;
// free is number of unused elements after len used elements
// alloc size = len + free
// But for memoryview, 'free' is reused as offset (in elements) into the
// parent object. (Union is not used to not go into a complication of
// union-of-bitfields with different toolchains). See comments in
// objarray.c.
size_t free : (8 * sizeof(size_t) - 8);
size_t len; // in elements
void *items;