309359b32f
Before this change, if a matrix position was not present in the transform, various incorrect behaviors would happen: 1) In some cases out-of-bounds accesses: Note that the size of the`transform[]` array does not necessarily match the size of the matrix. So for example if key position (ZMK_MATRIX_COLS-1, ZMK_MATRIX_ROWS-1) is not present in the transform, but ends up being pressed, then the array will be accessed beyond its size, and any data could be returned. 2) In other cases the 0th position in the keymap will be used because the `transform[]` array is initialized to all zeros.
66 lines
2.2 KiB
C
66 lines
2.2 KiB
C
/*
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* Copyright (c) 2020 The ZMK Contributors
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*
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* SPDX-License-Identifier: MIT
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*/
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#include <zephyr/kernel.h>
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#include <zmk/matrix_transform.h>
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#include <zmk/matrix.h>
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#include <dt-bindings/zmk/matrix_transform.h>
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#ifdef ZMK_KEYMAP_TRANSFORM_NODE
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/* the transform in the device tree is a list of (row,column) pairs that is
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* indexed by by the keymap position of that key. We want to invert this in
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* order to be able to quickly determine what keymap position a particular
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* row,column pair is associated with, using a single lookup.
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*
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* We do this by creating the `transform` array at compile time, which is
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* indexed by (row * ZMK_MATRIX_COLS) + column, and the value contains an
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* encoded keymap index it is associated with. The keymap index is encoded
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* by adding INDEX_OFFSET to it, because not all row,column pairs have an
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* associated keymap index (some matrices are sparse), C globals are
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* initialized to 0, and the keymap index of 0 is a valid index. We want to
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* be able to detect the condition when an unassigned matrix position is
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* pressed and we want to return an error.
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*/
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#define INDEX_OFFSET 1
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#define TRANSFORM_ENTRY(i, _) \
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[(KT_ROW(DT_PROP_BY_IDX(ZMK_KEYMAP_TRANSFORM_NODE, map, i)) * ZMK_MATRIX_COLS) + \
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KT_COL(DT_PROP_BY_IDX(ZMK_KEYMAP_TRANSFORM_NODE, map, i))] = i + INDEX_OFFSET
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static uint32_t transform[] = {LISTIFY(ZMK_KEYMAP_LEN, TRANSFORM_ENTRY, (, ), 0)};
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#endif
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int32_t zmk_matrix_transform_row_column_to_position(uint32_t row, uint32_t column) {
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#if DT_NODE_HAS_PROP(ZMK_KEYMAP_TRANSFORM_NODE, col_offset)
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column += DT_PROP(ZMK_KEYMAP_TRANSFORM_NODE, col_offset);
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#endif
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#if DT_NODE_HAS_PROP(ZMK_KEYMAP_TRANSFORM_NODE, row_offset)
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row += DT_PROP(ZMK_KEYMAP_TRANSFORM_NODE, row_offset);
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#endif
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const uint32_t matrix_index = (row * ZMK_MATRIX_COLS) + column;
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#ifdef ZMK_KEYMAP_TRANSFORM_NODE
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if (matrix_index >= ARRAY_SIZE(transform)) {
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return -EINVAL;
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}
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const uint32_t value = transform[matrix_index];
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if (!value) {
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return -EINVAL;
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}
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return value - INDEX_OFFSET;
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#else
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return matrix_index;
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#endif /* ZMK_KEYMAP_TRANSFORM_NODE */
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};
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