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Add start and end kwargs to writeto and readfrom_into so a single buffer can be used to save memory.

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This commit is contained in:
Scott Shawcroft 2016-11-28 18:35:19 -08:00
parent a319ac2f4e
commit 78f8565270
1 changed files with 61 additions and 14 deletions
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75
shared-bindings/nativeio/I2C.c
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@ -98,9 +98,11 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(nativeio_i2c_obj___exit___obj, 4, 4,
//| .. method:: I2C.scan()
//|
//| Scan all I2C addresses between 0x08 and 0x77 inclusive and return a list of
//| those that respond. A device responds if it pulls the SDA line low after
//| its address (including a read bit) is sent on the bus.
//| Scan all I2C addresses between 0x08 and 0x77 inclusive and return a
//| list of those that respond.
//|
//| :return: List of device ids on the I2C bus
//| :rtype: list
//|
STATIC mp_obj_t nativeio_i2c_scan(mp_obj_t self_in) {
nativeio_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
@ -116,31 +118,69 @@ STATIC mp_obj_t nativeio_i2c_scan(mp_obj_t self_in) {
}
MP_DEFINE_CONST_FUN_OBJ_1(nativeio_i2c_scan_obj, nativeio_i2c_scan);
//| .. method:: I2C.readfrom_into(address, buffer)
//| .. method:: I2C.readfrom_into(address, buffer, \*, start=0, end=len(buffer))
//|
//| Read into ``buffer`` from the slave specified by ``address``.
//| The number of bytes read will be the length of `buf`.
//| The number of bytes read will be the length of ``buffer``.
//|
STATIC mp_obj_t nativeio_i2c_readfrom_into(mp_obj_t self_in, mp_obj_t addr_in, mp_obj_t buf_in) {
nativeio_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
//| If ``start`` or ``end`` is provided, then the buffer will be sliced
//| as if ``buffer[start:end]``. This will not cause an allocation like
//| ``buf[start:end]`` will so it saves memory.
//|
//| :param int address: 7-bit device address
//| :param bytearray buffer: buffer to write into
//| :param int start: Index to start writing at
//| :param int end: Index to write up to but not include
//|
STATIC mp_obj_t nativeio_i2c_readfrom_into(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
enum { ARG_address, ARG_buffer, ARG_start, ARG_end };
static const mp_arg_t allowed_args[] = {
{ MP_QSTR_address, MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_buffer, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
{ MP_QSTR_start, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_end, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = INT_MAX} },
};
nativeio_i2c_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
mp_buffer_info_t bufinfo;
mp_get_buffer_raise(buf_in, &bufinfo, MP_BUFFER_WRITE);
common_hal_nativeio_i2c_read(self, mp_obj_get_int(addr_in), (uint8_t*)bufinfo.buf, bufinfo.len);
mp_get_buffer_raise(args[ARG_buffer].u_obj, &bufinfo, MP_BUFFER_WRITE);
int32_t end = args[ARG_end].u_int;
if (end < 0) {
end += bufinfo.len;
}
uint32_t len = max(0, min((int32_t) bufinfo.len, end - args[ARG_start].u_int));
int32_t start = args[ARG_start].u_int;
common_hal_nativeio_i2c_read(self, args[ARG_address].u_int, ((uint8_t*)bufinfo.buf) + start, len);
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_3(nativeio_i2c_readfrom_into_obj, nativeio_i2c_readfrom_into);
MP_DEFINE_CONST_FUN_OBJ_KW(nativeio_i2c_readfrom_into_obj, 3, nativeio_i2c_readfrom_into);
//| .. method:: I2C.writeto(address, buffer, stop=True)
//| .. method:: I2C.writeto(address, buffer, \*, start=0, end=len(buffer), stop=True)
//|
//| Write the bytes from ``buffer`` to the slave specified by ``address``.
//| Transmits a stop bit if ``stop`` is set.
//|
//| If ``start`` or ``end`` is provided, then the buffer will be sliced
//| as if ``buffer[start:end]``. This will not cause an allocation like
//| ``buffer[start:end]`` will so it saves memory.
//|
//| :param int address: 7-bit device address
//| :param bytearray buffer: buffer containing the bytes to write
//| :param int start: Index to start writing from
//| :param int end: Index to read up to but not include
//| :param bool stop: If true, output an I2C stop condition after the
//| buffer is written
//|
STATIC mp_obj_t nativeio_i2c_writeto(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
enum { ARG_address, ARG_buffer, ARG_stop };
enum { ARG_address, ARG_buffer, ARG_start, ARG_end, ARG_stop };
static const mp_arg_t allowed_args[] = {
{ MP_QSTR_address, MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_buffer, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
{ MP_QSTR_stop, MP_ARG_BOOL, {.u_bool = true} },
{ MP_QSTR_start, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_end, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = INT_MAX} },
{ MP_QSTR_stop, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = true} },
};
nativeio_i2c_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
@ -150,9 +190,16 @@ STATIC mp_obj_t nativeio_i2c_writeto(size_t n_args, const mp_obj_t *pos_args, mp
mp_buffer_info_t bufinfo;
mp_get_buffer_raise(args[ARG_buffer].u_obj, &bufinfo, MP_BUFFER_READ);
int32_t end = args[ARG_end].u_int;
if (end < 0) {
end += bufinfo.len;
}
uint32_t len = max(0, min((int32_t) bufinfo.len, end - args[ARG_start].u_int));
int32_t start = args[ARG_start].u_int;
// do the transfer
bool ok = common_hal_nativeio_i2c_write(self, args[ARG_address].u_int,
bufinfo.buf, bufinfo.len, args[ARG_stop].u_bool);
((uint8_t*) bufinfo.buf) + start, len, args[ARG_stop].u_bool);
if (!ok) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "I2C bus error"));
}