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extmod/machine_spi: Simplify SPI xfer function to only take one buf len.

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There is no need to take src_len and dest_len arguments.  The case of
reading-only with a single output byte (originally src_len=1, dest_len>1)
is now handled by using the output buffer as the input buffer, and using
memset to fill the output byte into this buffer.  This simplifies the
implementations of the spi_transfer protocol function.
This commit is contained in:
Damien George
2016-10-03 12:39:31 +11:00
parent a0d97fe408
commit 5bb28c7f10
5 changed files with 28 additions and 57 deletions
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25
extmod/machine_spi.c
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@@ -25,26 +25,24 @@
*/
#include <stdio.h>
#include <string.h>
#include "py/runtime.h"
#include "extmod/machine_spi.h"
#if MICROPY_PY_MACHINE_SPI
STATIC void mp_machine_spi_transfer(mp_obj_t self, size_t slen, const uint8_t *src, size_t dlen, uint8_t *dest) {
STATIC void mp_machine_spi_transfer(mp_obj_t self, size_t len, const void *src, void *dest) {
mp_obj_base_t *s = (mp_obj_base_t*)MP_OBJ_TO_PTR(self);
mp_machine_spi_p_t *spi_p = (mp_machine_spi_p_t*)s->type->protocol;
spi_p->transfer(s, slen, src, dlen, dest);
spi_p->transfer(s, len, src, dest);
}
STATIC mp_obj_t mp_machine_spi_read(size_t n_args, const mp_obj_t *args) {
uint8_t write_byte = 0;
if (n_args == 3) {
write_byte = mp_obj_get_int(args[2]);
}
vstr_t vstr;
vstr_init_len(&vstr, mp_obj_get_int(args[1]));
mp_machine_spi_transfer(args[0], 1, &write_byte, vstr.len, (uint8_t*)vstr.buf);
memset(vstr.buf, n_args == 3 ? mp_obj_get_int(args[2]) : 0, vstr.len);
mp_machine_spi_transfer(args[0], vstr.len, vstr.buf, vstr.buf);
return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_machine_spi_read_obj, 2, 3, mp_machine_spi_read);
@@ -52,11 +50,8 @@ MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_machine_spi_read_obj, 2, 3, mp_machine_sp
STATIC mp_obj_t mp_machine_spi_readinto(size_t n_args, const mp_obj_t *args) {
mp_buffer_info_t bufinfo;
mp_get_buffer_raise(args[1], &bufinfo, MP_BUFFER_WRITE);
uint8_t write_byte = 0;
if (n_args == 3) {
write_byte = mp_obj_get_int(args[2]);
}
mp_machine_spi_transfer(args[0], 1, &write_byte, bufinfo.len, (uint8_t*)bufinfo.buf);
memset(bufinfo.buf, n_args == 3 ? mp_obj_get_int(args[2]) : 0, bufinfo.len);
mp_machine_spi_transfer(args[0], bufinfo.len, bufinfo.buf, bufinfo.buf);
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_machine_spi_readinto_obj, 2, 3, mp_machine_spi_readinto);
@@ -64,7 +59,7 @@ MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_machine_spi_readinto_obj, 2, 3, mp_machin
STATIC mp_obj_t mp_machine_spi_write(mp_obj_t self, mp_obj_t wr_buf) {
mp_buffer_info_t src;
mp_get_buffer_raise(wr_buf, &src, MP_BUFFER_READ);
mp_machine_spi_transfer(self, src.len, (const uint8_t*)src.buf, 0, NULL);
mp_machine_spi_transfer(self, src.len, (const uint8_t*)src.buf, NULL);
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_2(mp_machine_spi_write_obj, mp_machine_spi_write);
@@ -75,9 +70,9 @@ STATIC mp_obj_t mp_machine_spi_write_readinto(mp_obj_t self, mp_obj_t wr_buf, mp
mp_buffer_info_t dest;
mp_get_buffer_raise(rd_buf, &dest, MP_BUFFER_WRITE);
if (src.len != dest.len) {
nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "buffers must be the same length"));
mp_raise_ValueError("buffers must be the same length");
}
mp_machine_spi_transfer(self, src.len, (const uint8_t*)src.buf, dest.len, (uint8_t*)dest.buf);
mp_machine_spi_transfer(self, src.len, src.buf, dest.buf);
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_3(mp_machine_spi_write_readinto_obj, mp_machine_spi_write_readinto);