Modify mjSORT to remove some unnecessary copies.
PiperOrigin-RevId: 781573097 Change-Id: I60148bc88fb64ea6dfee9390efb3fd161ad3f1d8
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Copybara-Service
parent
365cac49f8
commit
58c95219dc
+14
-13
@@ -32,22 +32,18 @@
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// sub-macro that merges two sub-sorted arrays [start, ..., mid), [mid, ..., end) together
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#define _mjMERGE(type, arr, buf, start, mid, end, cmp, context) \
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#define _mjMERGE(type, src, dest, start, mid, end, cmp, context) \
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{ \
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int len1 = mid - start, len2 = end - mid; \
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type* left = buf, *right = buf + len1; \
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for (int i = 0; i < len1; i++) left[i] = arr[start + i]; \
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for (int i = 0; i < len2; i++) right[i] = arr[mid + i]; \
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int i = 0, j = 0, k = start; \
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while (i < len1 && j < len2) { \
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if (cmp(left + i, right + j, context) <= 0) { \
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arr[k++] = left[i++]; \
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int i = start, j = mid, k = start; \
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while (i < mid && j < end) { \
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if (cmp(src + i, src + j, context) <= 0) { \
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dest[k++] = src[i++]; \
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} else { \
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arr[k++] = right[j++]; \
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dest[k++] = src[j++]; \
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} \
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} \
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while (i < len1) arr[k++] = left[i++]; \
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while (j < len2) arr[k++] = right[j++]; \
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if (i < mid) memcpy(dest + k, src + i, (mid - i) * sizeof(type)); \
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else if (j < end) memcpy(dest + k, src + j, (end - j) * sizeof(type)); \
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}
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// defines an inline stable sorting function via tiled merge sorting (timsort)
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@@ -60,15 +56,20 @@
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int end = (start + _mjRUNSIZE < n) ? start + _mjRUNSIZE : n; \
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_mjINSERTION_SORT(type, arr, start, end, cmp, context); \
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} \
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type* src = arr, *dest = buf, *tmp; \
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for (int len = _mjRUNSIZE; len < n; len *= 2) { \
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for (int start = 0; start < n; start += 2*len) { \
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int mid = start + len; \
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int end = (start + 2*len < n) ? start + 2*len : n; \
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if (mid < end) { \
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_mjMERGE(type, arr, buf, start, mid, end, cmp, context); \
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_mjMERGE(type, src, dest, start, mid, end, cmp, context); \
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} else { \
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memcpy(dest + start, src + start, (end - start) * sizeof(type)); \
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} \
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} \
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tmp = src; src = dest; dest = tmp; \
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} \
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if (src != arr) memcpy(arr, src, n * sizeof(type)); \
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}
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#endif // MUJOCO_SRC_ENGINE_ENGINE_SORT_H_
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