#define ALL_EQ(v1, v2) ((v1) == (v2))
#endif
+#define BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR 8
+static inline bool
+can_use_buffer_find_nonzero_offset(const void *buf, size_t len)
+{
+ return (len % (BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR
+ * sizeof(VECTYPE)) == 0
+ && ((uintptr_t) buf) % sizeof(VECTYPE) == 0);
+}
+size_t buffer_find_nonzero_offset(const void *buf, size_t len);
+
#endif
#endif
}
+/*
+ * Searches for an area with non-zero content in a buffer
+ *
+ * Attention! The len must be a multiple of
+ * BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR * sizeof(VECTYPE)
+ * and addr must be a multiple of sizeof(VECTYPE) due to
+ * restriction of optimizations in this function.
+ *
+ * can_use_buffer_find_nonzero_offset() can be used to check
+ * these requirements.
+ *
+ * The return value is the offset of the non-zero area rounded
+ * down to a multiple of sizeof(VECTYPE) for the first
+ * BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR chunks and down to
+ * BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR * sizeof(VECTYPE)
+ * afterwards.
+ *
+ * If the buffer is all zero the return value is equal to len.
+ */
+
+size_t buffer_find_nonzero_offset(const void *buf, size_t len)
+{
+ const VECTYPE *p = buf;
+ const VECTYPE zero = (VECTYPE){0};
+ size_t i;
+
+ assert(can_use_buffer_find_nonzero_offset(buf, len));
+
+ if (!len) {
+ return 0;
+ }
+
+ for (i = 0; i < BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR; i++) {
+ if (!ALL_EQ(p[i], zero)) {
+ return i * sizeof(VECTYPE);
+ }
+ }
+
+ for (i = BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR;
+ i < len / sizeof(VECTYPE);
+ i += BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR) {
+ VECTYPE tmp0 = p[i + 0] | p[i + 1];
+ VECTYPE tmp1 = p[i + 2] | p[i + 3];
+ VECTYPE tmp2 = p[i + 4] | p[i + 5];
+ VECTYPE tmp3 = p[i + 6] | p[i + 7];
+ VECTYPE tmp01 = tmp0 | tmp1;
+ VECTYPE tmp23 = tmp2 | tmp3;
+ if (!ALL_EQ(tmp01 | tmp23, zero)) {
+ break;
+ }
+ }
+
+ return i * sizeof(VECTYPE);
+}
+
/*
* Checks if a buffer is all zeroes
*