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DT_INST_STRING_TOKEN_BY_IDX_OR macro #97404

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DT_INST_STRING_TOKEN_BY_IDX_OR macro #97404

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b6b2aa0
zephyr: devicetree: add new macros
KozhinovAlexander Oct 11, 2025
dd76b5c
tests: lib: devicetree: api: add new macro tests
KozhinovAlexander Oct 12, 2025
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24 changes: 24 additions & 0 deletions include/zephyr/devicetree.h
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@
* SPDX-License-Identifier: Apache-2.0
* Copyright (c) 2020 Nordic Semiconductor
* Copyright (c) 2020, Linaro Ltd.
* Copyright (c) 2025 Alexander Kozhinov <[email protected]>
*
* Not a generated file. Feel free to modify.
*/
Expand Down Expand Up @@ -1322,6 +1323,18 @@
#define DT_STRING_TOKEN_BY_IDX(node_id, prop, idx) \
DT_CAT6(node_id, _P_, prop, _IDX_, idx, _STRING_TOKEN)

/**
* @brief Like DT_STRING_TOKEN_BY_IDX(), but with a fallback to default_value
* @param node_id node identifier
* @param prop lowercase-and-underscores property name
* @param idx the index to get
* @param default_value a fallback value to expand to
* @return the element in @p prop at index @p idx as a token
*/
#define DT_STRING_TOKEN_BY_IDX_OR(node_id, prop, idx, default_value) \
COND_CODE_1(DT_PROP_HAS_IDX(node_id, prop, idx), \
(DT_STRING_TOKEN_BY_IDX(node_id, prop, idx)), (default_value))

/**
* @brief Like DT_STRING_TOKEN_BY_IDX(), but uppercased.
*
Expand Down Expand Up @@ -4418,6 +4431,17 @@
#define DT_INST_STRING_TOKEN_BY_IDX(inst, prop, idx) \
DT_STRING_TOKEN_BY_IDX(DT_DRV_INST(inst), prop, idx)

/**
* @brief Like DT_INST_STRING_TOKEN_BY_IDX(), but with a fallback to default_value
* @param inst instance number
* @param prop lowercase-and-underscores property name
* @param idx the index to get
* @param default_value a fallback value to expand to
* @return the element in @p prop at index @p idx as a token
*/
#define DT_INST_STRING_TOKEN_BY_IDX_OR(inst, prop, idx, default_value) \
DT_STRING_TOKEN_BY_IDX_OR(DT_DRV_INST(inst), prop, idx, default_value)

/**
* @brief Like DT_INST_STRING_TOKEN_BY_IDX(), but uppercased.
* @param inst instance number
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18 changes: 18 additions & 0 deletions tests/lib/devicetree/api/src/main.c
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Expand Up @@ -3433,7 +3433,9 @@ ZTEST(devicetree_api, test_string_token)
#define DT_DRV_COMPAT vnd_string_array_token
ZTEST(devicetree_api, test_string_idx_token)
{
/* The enum has 7 values in total - thus invalid idx starts with 16 */
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Copilot AI Oct 12, 2025

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The comment states invalid indices start with 16, but the test uses index 42 for out-of-range testing. Either update the comment to reflect the actual test values or explain why 42 was chosen instead of 16.

Suggested change
/* The enum has 7 values in total - thus invalid idx starts with 16 */
/* The enum has 16 values in total (indices 0-15), so invalid indices start at 16.
* The test uses index 42 for out-of-range testing to ensure it is well beyond the valid range.
*/

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The number 42 is famously known as "The Answer to the Ultimate Question of Life, the Universe, and Everything"

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the robot has a point though that 16 is probably better for test to avoid off by one errors

enum token_string_idx {
token_idx_default,
/* Tokens */
token_first_idx_zero,
token_first_idx_one,
Expand Down Expand Up @@ -3468,6 +3470,15 @@ ZTEST(devicetree_api, test_string_idx_token)
zassert_equal(DT_STRING_TOKEN_BY_IDX(DT_NODELABEL(test_str_array_token_1), val, 3),
token_second_idx_three, "");

/* Index is in range */
zassert_equal(DT_STRING_TOKEN_BY_IDX_OR(DT_NODELABEL(test_str_array_token_1), val, 3,
token_idx_default),
token_second_idx_three, "");
/* Index is out of range */
zassert_equal(DT_STRING_TOKEN_BY_IDX_OR(DT_NODELABEL(test_str_array_token_1), val, 42,
token_idx_default),
token_idx_default, "");

zassert_equal(DT_STRING_UPPER_TOKEN_BY_IDX(DT_NODELABEL(test_str_array_token_0), val, 0),
TOKEN_FIRST_IDX_ZERO, "");
zassert_equal(DT_STRING_UPPER_TOKEN_BY_IDX(DT_NODELABEL(test_str_array_token_0), val, 1),
Expand Down Expand Up @@ -3506,6 +3517,13 @@ ZTEST(devicetree_api, test_string_idx_token)
zassert_equal(STRING_TOKEN_BY_IDX_VAR(DT_NODELABEL(test_str_array_token_1))[2],
token_second_idx_two, "");

/* Index is in range instance #0 corresponds to test_str_array_token_0 */
zassert_equal(DT_INST_STRING_TOKEN_BY_IDX_OR(0, val, 2, token_idx_default),
token_first_idx_two, "");
/* Index is out of range */
zassert_equal(DT_INST_STRING_TOKEN_BY_IDX_OR(0, val, 21, token_idx_default),
token_idx_default, "");

#define STRING_UPPER_TOKEN_BY_IDX_VAR(node_id) _CONCAT(var_upper_token, node_id)
#define STRING_UPPER_TOKEN_BY_IDX_TEST_INST_EXPANSION(inst) \
enum token_string_idx STRING_UPPER_TOKEN_BY_IDX_VAR(DT_DRV_INST(inst))[] = { \
Expand Down