bitops: rename from _bit_transpose, describe the algorithm

10 files changed, 122 insertions, 121 deletions

diff --git a/locale/circuitpython.pot b/locale/circuitpython.pot
index eef1b07f2..b1bc1a390 100644
--- a/locale/circuitpython.pot
+++ b/locale/circuitpython.pot
@@ -1092,7 +1092,7 @@ msgstr ""
 msgid "Initialization failed due to lack of memory"
 msgstr ""
 
-#: shared-bindings/_bit_transpose/__init__.c
+#: shared-bindings/bitops/__init__.c
 #, c-format
 msgid "Input buffer length (%d) must be a multiple of the strand count (%d)"
 msgstr ""
@@ -1664,7 +1664,7 @@ msgstr ""
 msgid "Out of sockets"
 msgstr ""
 
-#: shared-bindings/_bit_transpose/__init__.c
+#: shared-bindings/bitops/__init__.c
 #, c-format
 msgid "Output buffer must be at least %d bytes"
 msgstr ""
@@ -3475,10 +3475,6 @@ msgstr ""
 msgid "not enough arguments for format string"
 msgstr ""
 
-#: shared-bindings/_bit_transpose/__init__.c
-msgid "num_strands must be from 2 to 8 (inclusive)"
-msgstr ""
-
 #: extmod/ulab/code/ulab_create.c
 msgid "number of points must be at least 2"
 msgstr ""
@@ -4115,6 +4111,10 @@ msgstr ""
 msgid "watchdog timeout must be greater than 0"
 msgstr ""
 
+#: shared-bindings/bitops/__init__.c
+msgid "width must be from 2 to 8 (inclusive)"
+msgstr ""
+
 #: shared-bindings/rgbmatrix/RGBMatrix.c
 msgid "width must be greater than zero"
 msgstr ""
diff --git a/ports/raspberrypi/mpconfigport.mk b/ports/raspberrypi/mpconfigport.mk
index 6bd617f37..b93e4dcc7 100644
--- a/ports/raspberrypi/mpconfigport.mk
+++ b/ports/raspberrypi/mpconfigport.mk
@@ -24,7 +24,7 @@ CIRCUITPY_NEOPIXEL_WRITE = 0
 endif
 
 CIRCUITPY_FULL_BUILD = 1
-CIRCUITPY_BIT_TRANSPOSE = 1
+CIRCUITPY_BITOPS = 1
 CIRCUITPY_PWMIO = 1
 
 # Things that need to be implemented.
diff --git a/py/circuitpy_defns.mk b/py/circuitpy_defns.mk
index e04031e5a..c1cf86362 100644
--- a/py/circuitpy_defns.mk
+++ b/py/circuitpy_defns.mk
@@ -132,9 +132,9 @@ endif
 ifeq ($(CIRCUITPY_AUDIOMP3),1)
 SRC_PATTERNS += audiomp3/%
 endif
-ifeq ($(CIRCUITPY_BIT_TRANSPOSE),1)
-$(info BIT_TRANSPOSE enabled)
-SRC_PATTERNS += _bit_transpose/%
+ifeq ($(CIRCUITPY_BITOPS),1)
+$(info BITOPS enabled)
+SRC_PATTERNS += bitops/%
 endif
 ifeq ($(CIRCUITPY_BITBANGIO),1)
 SRC_PATTERNS += bitbangio/%
@@ -444,7 +444,6 @@ SRC_BINDINGS_ENUMS += \
 	util.c
 
 SRC_SHARED_MODULE_ALL = \
-	_bit_transpose/__init__.c \
 	_bleio/Address.c \
 	_bleio/Attribute.c \
 	_bleio/ScanEntry.c \
@@ -471,6 +470,7 @@ SRC_SHARED_MODULE_ALL = \
 	bitbangio/OneWire.c \
 	bitbangio/SPI.c \
 	bitbangio/__init__.c \
+	bitops/__init__.c \
 	board/__init__.c \
 	adafruit_bus_device/__init__.c \
 	adafruit_bus_device/I2CDevice.c \
diff --git a/py/circuitpy_mpconfig.h b/py/circuitpy_mpconfig.h
index be95eabe2..d72146c42 100644
--- a/py/circuitpy_mpconfig.h
+++ b/py/circuitpy_mpconfig.h
@@ -299,11 +299,11 @@ extern const struct _mp_obj_module_t audiopwmio_module;
 #define BINASCII_MODULE
 #endif
 
-#if CIRCUITPY_BIT_TRANSPOSE
-extern const struct _mp_obj_module_t bit_transpose_module;
-#define BIT_TRANSPOSE_MODULE        { MP_OBJ_NEW_QSTR(MP_QSTR__bit_transpose),(mp_obj_t)&bit_transpose_module },
+#if CIRCUITPY_BITOPS
+extern const struct _mp_obj_module_t bitops_module;
+#define BITOPS_MODULE        { MP_OBJ_NEW_QSTR(MP_QSTR_bitops),(mp_obj_t)&bitops_module },
 #else
-#define BIT_TRANSPOSE_MODULE
+#define BITOPS_MODULE
 #endif
 
 
@@ -827,7 +827,7 @@ extern const struct _mp_obj_module_t msgpack_module;
     AUDIOMP3_MODULE \
     AUDIOPWMIO_MODULE \
     BINASCII_MODULE \
-    BIT_TRANSPOSE_MODULE \
+    BITOPS_MODULE \
     BITBANGIO_MODULE \
     BLEIO_MODULE \
     BOARD_MODULE \
diff --git a/py/circuitpy_mpconfig.mk b/py/circuitpy_mpconfig.mk
index f06e99b57..6244ed136 100644
--- a/py/circuitpy_mpconfig.mk
+++ b/py/circuitpy_mpconfig.mk
@@ -89,8 +89,8 @@ CFLAGS += -DCIRCUITPY_AUDIOMP3=$(CIRCUITPY_AUDIOMP3)
 CIRCUITPY_BINASCII ?= $(CIRCUITPY_FULL_BUILD)
 CFLAGS += -DCIRCUITPY_BINASCII=$(CIRCUITPY_BINASCII)
 
-CIRCUITPY_BIT_TRANSPOSE ?= 0
-CFLAGS += -DCIRCUITPY_BIT_TRANSPOSE=$(CIRCUITPY_BIT_TRANSPOSE)
+CIRCUITPY_BITOPS ?= 0
+CFLAGS += -DCIRCUITPY_BITOPS=$(CIRCUITPY_BITOPS)
 
 CIRCUITPY_BITBANGIO ?= $(CIRCUITPY_FULL_BUILD)
 CFLAGS += -DCIRCUITPY_BITBANGIO=$(CIRCUITPY_BITBANGIO)
diff --git a/shared-bindings/_bit_transpose/__init__.c b/shared-bindings/_bit_transpose/__init__.c
deleted file mode 100644
index 0b9d31fbe..000000000
--- a/shared-bindings/_bit_transpose/__init__.c
+++ /dev/null
@@ -1,100 +0,0 @@
-/*
- * This file is part of the Circuit Python project, https://github.com/adafruit/circuitpython
- *
- * The MIT License (MIT)
- *
- * Copyright (c) 2018 Roy Hooper
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-
-#include "py/obj.h"
-#include "py/runtime.h"
-
-#include "shared-bindings/_bit_transpose/__init__.h"
-
-//| """A fast bit transposition function for parallel NeoPixel strips
-//|
-//| When driving multiple NeoPixel strips from a shift register, the bits
-//| must be re-ordered in a specific way.  This module offers a low-level
-//| routine for performing the transformation."""
-//|
-
-//| def bit_transpose(input: _typing.ReadableBuffer, *, num_strands:int = 8, output: Optional[_typing.WriteableBuffer]=None) -> WriteableBuffer:
-//|     """Convert a sequence of pixel values into a single stream of bytes suitable for sending via a parallel conversion method (PioPixl8)
-//|
-//|     The number of bytes in the input buffer must be a multiple of the number of strands.
-//|
-//|     If specified output buffer must be big enough for the output, ``len(input) * 8  // num_strands``.  To get a properly sized buffer,
-//|     you can also pass in ``output=None`` once, then re-use the return value in future calls.
-//|
-//|     Returns the output buffer if specified (which must be big enough to hold the result), otherwise a freshly allocated buffer."""
-//|     ...
-//|
-STATIC mp_obj_t bit_transpose(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
-    enum { ARG_input, ARG_num_strands, ARG_output };
-    static const mp_arg_t allowed_args[] = {
-        { MP_QSTR_input, MP_ARG_OBJ | MP_ARG_REQUIRED, {} },
-        { MP_QSTR_num_strands, MP_ARG_INT | MP_ARG_KW_ONLY, { .u_int = 8 } },
-        { MP_QSTR_output, MP_ARG_OBJ | MP_ARG_KW_ONLY, { .u_obj = mp_const_none } },
-    };
-    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);
-
-    mp_buffer_info_t input_bufinfo;
-    mp_buffer_info_t output_bufinfo;
-
-    mp_get_buffer_raise(args[ARG_input].u_obj, &input_bufinfo, MP_BUFFER_READ);
-    int num_strands = args[ARG_num_strands].u_int;
-
-    if (num_strands < 2 || num_strands > 8) {
-        mp_raise_ValueError(translate("num_strands must be from 2 to 8 (inclusive)"));
-    }
-
-    int inlen = input_bufinfo.len;
-    if (inlen % num_strands != 0) {
-        mp_raise_ValueError_varg(translate("Input buffer length (%d) must be a multiple of the strand count (%d)"), inlen, num_strands);
-    }
-    mp_obj_t output = args[ARG_output].u_obj;
-
-    int outlen = 8 * (inlen / num_strands);
-    if (!output || output == mp_const_none) {
-        output = mp_obj_new_bytearray_of_zeros(outlen);
-    }
-    mp_get_buffer_raise(output, &output_bufinfo, MP_BUFFER_WRITE);
-    int avail = output_bufinfo.len;
-    if (avail < outlen) {
-        mp_raise_ValueError_varg(translate("Output buffer must be at least %d bytes"), outlen);
-    }
-    common_hal_bit_transpose_bit_transpose(output_bufinfo.buf, input_bufinfo.buf, inlen, num_strands);
-    return output;
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_KW(bit_transpose_bit_transpose_obj, 1, bit_transpose);
-
-STATIC const mp_rom_map_elem_t bit_transpose_module_globals_table[] = {
-    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR__bit_transpose) },
-    { MP_ROM_QSTR(MP_QSTR_bit_transpose), MP_ROM_PTR(&bit_transpose_bit_transpose_obj) },
-};
-
-STATIC MP_DEFINE_CONST_DICT(bit_transpose_module_globals, bit_transpose_module_globals_table);
-
-const mp_obj_module_t bit_transpose_module = {
-    .base = { &mp_type_module },
-    .globals = (mp_obj_dict_t*)&bit_transpose_module_globals,
-};
diff --git a/shared-bindings/bitops/__init__.c b/shared-bindings/bitops/__init__.c
new file mode 100644
index 000000000..fc5784259
--- /dev/null
+++ b/shared-bindings/bitops/__init__.c
@@ -0,0 +1,101 @@
+/*
+ * This file is part of the Circuit Python project, https://github.com/adafruit/circuitpython
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Roy Hooper
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/obj.h"
+#include "py/runtime.h"
+
+#include "shared-bindings/bitops/__init__.h"
+
+//| """Routines for low-level manipulation of binary data"""
+//|
+//|
+
+//| def bit_transpose(input: _typing.ReadableBuffer, *, width:int = 8, output: Optional[_typing.WriteableBuffer]=None) -> WriteableBuffer:
+//|     """"Transpose" a buffer by assembling each output byte with bits taken from each of ``width`` different input bytes.
+//|
+//|     This can be useful to convert a sequence of pixel values into a single
+//|     stream of bytes suitable for sending via a parallel conversion method.
+//|
+//|     The number of bytes in the input buffer must be a multiple of the width,
+//|     and the width can be any value from 2 to 8.  If the width is fewer than 8,
+//|     then the remaining (less significant) bits of the output are set to zero.
+//|
+//|     Let ``stride = len(input)//width``.  Then the first byte is made out of the
+//|     most significant bits of ``[input[0], input[stride], input[2*stride], ...]``.
+//|     The second byte is made out of the second bits, and so on until the 8th output
+//|     byte which is made of the first bits of ``input[1], input[1+stride,
+//|     input[2*stride], ...]``.
+//|
+//|     The required output buffer size is ``len(input) * 8  // width``.
+//|
+//|     Returns the output buffer."""
+//|     ...
+
+STATIC mp_obj_t bit_transpose(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    enum { ARG_input, ARG_width, ARG_output };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_input, MP_ARG_OBJ | MP_ARG_REQUIRED },
+        { MP_QSTR_output, MP_ARG_OBJ | MP_ARG_REQUIRED },
+        { MP_QSTR_width, MP_ARG_INT | MP_ARG_KW_ONLY, { .u_int = 8 } },
+    };
+    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);
+
+    int width = args[ARG_width].u_int;
+    if (width < 2 || width > 8) {
+        mp_raise_ValueError(translate("width must be from 2 to 8 (inclusive)"));
+    }
+
+    mp_buffer_info_t input_bufinfo;
+    mp_get_buffer_raise(args[ARG_input].u_obj, &input_bufinfo, MP_BUFFER_READ);
+    int inlen = input_bufinfo.len;
+    if (inlen % width != 0) {
+        mp_raise_ValueError_varg(translate("Input buffer length (%d) must be a multiple of the strand count (%d)"), inlen, width);
+    }
+
+    mp_buffer_info_t output_bufinfo;
+    mp_get_buffer_raise(args[ARG_output].u_obj, &output_bufinfo, MP_BUFFER_WRITE);
+    int avail = output_bufinfo.len;
+    int outlen = 8 * (inlen / width);
+    if (avail < outlen) {
+        mp_raise_ValueError_varg(translate("Output buffer must be at least %d bytes"), outlen);
+    }
+    common_hal_bitops_bit_transpose(output_bufinfo.buf, input_bufinfo.buf, inlen, width);
+    return args[ARG_output].u_obj;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(bitops_bit_transpose_obj, 1, bit_transpose);
+
+STATIC const mp_rom_map_elem_t bitops_module_globals_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_bitops) },
+    { MP_ROM_QSTR(MP_QSTR_bit_transpose), MP_ROM_PTR(&bitops_bit_transpose_obj) },
+};
+
+STATIC MP_DEFINE_CONST_DICT(bitops_module_globals, bitops_module_globals_table);
+
+const mp_obj_module_t bitops_module = {
+    .base = { &mp_type_module },
+    .globals = (mp_obj_dict_t*)&bitops_module_globals,
+};
diff --git a/shared-bindings/_bit_transpose/__init__.h b/shared-bindings/bitops/__init__.h
index 5fcf11d45..6654cac5e 100644
--- a/shared-bindings/_bit_transpose/__init__.h
+++ b/shared-bindings/bitops/__init__.h
@@ -29,4 +29,4 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-void common_hal_bit_transpose_bit_transpose(uint8_t *result, const uint8_t *src, size_t inlen, size_t num_strands);
+void common_hal_bitops_bit_transpose(uint8_t *result, const uint8_t *src, size_t inlen, size_t num_strands);
diff --git a/shared-module/_bit_transpose/__init__.c b/shared-module/bitops/__init__.c
index 517d2d840..66898e5be 100644
--- a/shared-module/_bit_transpose/__init__.c
+++ b/shared-module/bitops/__init__.c
@@ -24,7 +24,7 @@
  * THE SOFTWARE.
  */
 
-#include "shared-bindings/_bit_transpose/__init__.h"
+#include "shared-bindings/bitops/__init__.h"
 
 #include <stdint.h>
 #include <stdlib.h>
@@ -142,7 +142,7 @@ static void bit_transpose_var(uint32_t *result, const uint8_t *src, size_t src_s
     }
 }
 
-void common_hal_bit_transpose_bit_transpose(uint8_t *result, const uint8_t *src, size_t inlen, size_t num_strands) {
+void common_hal_bitops_bit_transpose(uint8_t *result, const uint8_t *src, size_t inlen, size_t num_strands) {
     if(num_strands == 8) {
         bit_transpose_8((uint32_t*)(void*)result, src, inlen/8, inlen/8);
     } else  {
diff --git a/shared-module/_bit_transpose/__init__.h b/shared-module/bitops/__init__.h
index 945e48b72..945e48b72 100644
--- a/shared-module/_bit_transpose/__init__.h
+++ b/shared-module/bitops/__init__.h