py/objringio: Add micropython.RingIO() interface for general use.

This commit adds a new `RingIO` type which exposes the internal ring-buffer
code for general use in Python programs.  It has the stream interface
making it similar to `StringIO` and `BytesIO`, except `RingIO` has a fixed
buffer size and is automatically safe when reads and writes are in
different threads or an IRQ.

This new type is enabled at the "extra features" ROM level.

Signed-off-by: Andrew Leech <andrew.leech@planetinnovation.com.au>

1 files changed, 130 insertions, 0 deletions

diff --git a/py/objringio.c b/py/objringio.c
new file mode 100644
index 0000000000..ba1ec25307
--- /dev/null
+++ b/py/objringio.c
@@ -0,0 +1,130 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2024 Andrew Leech
+ *
+ * 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 "ringbuf.h"
+#include "py/mpconfig.h"
+
+#if MICROPY_PY_MICROPYTHON_RINGIO
+
+#include "py/runtime.h"
+#include "py/stream.h"
+
+typedef struct _micropython_ringio_obj_t {
+    mp_obj_base_t base;
+    ringbuf_t ringbuffer;
+} micropython_ringio_obj_t;
+
+static mp_obj_t micropython_ringio_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    mp_arg_check_num(n_args, n_kw, 1, 1, false);
+    mp_int_t buff_size = -1;
+    mp_buffer_info_t bufinfo = {NULL, 0, 0};
+
+    if (!mp_get_buffer(args[0], &bufinfo, MP_BUFFER_RW)) {
+        buff_size = mp_obj_get_int(args[0]);
+    }
+    micropython_ringio_obj_t *self = mp_obj_malloc(micropython_ringio_obj_t, type);
+    if (bufinfo.buf != NULL) {
+        // buffer passed in, use it directly for ringbuffer.
+        self->ringbuffer.buf = bufinfo.buf;
+        self->ringbuffer.size = bufinfo.len;
+        self->ringbuffer.iget = self->ringbuffer.iput = 0;
+    } else {
+        // Allocate new buffer, add one extra to buff_size as ringbuf consumes one byte for tracking.
+        ringbuf_alloc(&(self->ringbuffer), buff_size + 1);
+    }
+    return MP_OBJ_FROM_PTR(self);
+}
+
+static mp_uint_t micropython_ringio_read(mp_obj_t self_in, void *buf_in, mp_uint_t size, int *errcode) {
+    micropython_ringio_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    size = MIN(size, ringbuf_avail(&self->ringbuffer));
+    ringbuf_memcpy_get_internal(&(self->ringbuffer), buf_in, size);
+    *errcode = 0;
+    return size;
+}
+
+static mp_uint_t micropython_ringio_write(mp_obj_t self_in, const void *buf_in, mp_uint_t size, int *errcode) {
+    micropython_ringio_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    size = MIN(size, ringbuf_free(&self->ringbuffer));
+    ringbuf_memcpy_put_internal(&(self->ringbuffer), buf_in, size);
+    *errcode = 0;
+    return size;
+}
+
+static mp_uint_t micropython_ringio_ioctl(mp_obj_t self_in, mp_uint_t request, uintptr_t arg, int *errcode) {
+    micropython_ringio_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    switch (request) {
+        case MP_STREAM_POLL: {
+            mp_uint_t ret = 0;
+            if ((arg & MP_STREAM_POLL_RD) && ringbuf_avail(&self->ringbuffer) > 0) {
+                ret |= MP_STREAM_POLL_RD;
+            }
+            if ((arg & MP_STREAM_POLL_WR) && ringbuf_free(&self->ringbuffer) > 0) {
+                ret |= MP_STREAM_POLL_WR;
+            }
+            return ret;
+        }
+        case MP_STREAM_CLOSE:
+            return 0;
+    }
+    *errcode = MP_EINVAL;
+    return MP_STREAM_ERROR;
+}
+
+static mp_obj_t micropython_ringio_any(mp_obj_t self_in) {
+    micropython_ringio_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    return MP_OBJ_NEW_SMALL_INT(ringbuf_avail(&self->ringbuffer));
+}
+static MP_DEFINE_CONST_FUN_OBJ_1(micropython_ringio_any_obj, micropython_ringio_any);
+
+static const mp_rom_map_elem_t micropython_ringio_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_any), MP_ROM_PTR(&micropython_ringio_any_obj) },
+    { MP_ROM_QSTR(MP_QSTR_read), MP_ROM_PTR(&mp_stream_read_obj) },
+    { MP_ROM_QSTR(MP_QSTR_readline), MP_ROM_PTR(&mp_stream_unbuffered_readline_obj) },
+    { MP_ROM_QSTR(MP_QSTR_readinto), MP_ROM_PTR(&mp_stream_readinto_obj) },
+    { MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&mp_stream_write_obj) },
+    { MP_ROM_QSTR(MP_QSTR_close), MP_ROM_PTR(&mp_stream_close_obj) },
+
+};
+static MP_DEFINE_CONST_DICT(micropython_ringio_locals_dict, micropython_ringio_locals_dict_table);
+
+static const mp_stream_p_t ringio_stream_p = {
+    .read = micropython_ringio_read,
+    .write = micropython_ringio_write,
+    .ioctl = micropython_ringio_ioctl,
+    .is_text = false,
+};
+
+MP_DEFINE_CONST_OBJ_TYPE(
+    mp_type_ringio,
+    MP_QSTR_RingIO,
+    MP_TYPE_FLAG_NONE,
+    make_new, micropython_ringio_make_new,
+    protocol, &ringio_stream_p,
+    locals_dict, &micropython_ringio_locals_dict
+    );
+
+#endif // MICROPY_PY_MICROPYTHON_RINGIO