| /* |
| * strncmp - compare two strings with limit |
| * |
| * Copyright (c) 2018, Arm Limited. |
| * SPDX-License-Identifier: MIT |
| */ |
| |
| #include "../asmdefs.h" |
| |
| #if __ARM_FEATURE_SVE |
| /* Assumptions: |
| * |
| * ARMv8-a, AArch64 |
| * SVE Available. |
| */ |
| |
| .arch armv8-a+sve |
| .text |
| |
| ENTRY_ALIGN (__strncmp_aarch64_sve, 4) |
| setffr /* initialize FFR */ |
| mov x3, 0 /* initialize off */ |
| |
| 0: whilelo p0.b, x3, x2 /* while off < max */ |
| b.none 9f |
| |
| ldff1b z0.b, p0/z, [x0, x3] |
| ldff1b z1.b, p0/z, [x1, x3] |
| rdffrs p1.b, p0/z |
| b.nlast 2f |
| |
| /* First fault did not fail: the vector up to max is valid. |
| Avoid depending on the contents of FFR beyond the branch. |
| Increment for a whole vector, even if we've only read a partial. |
| This is significantly cheaper than INCP, and since OFF is not |
| used after the loop it is ok to increment OFF past MAX. */ |
| incb x3 |
| cmpeq p1.b, p0/z, z0.b, z1.b /* compare strings */ |
| cmpne p2.b, p0/z, z0.b, 0 /* search for ~zero */ |
| nands p2.b, p0/z, p1.b, p2.b /* ~(eq & ~zero) -> ne | zero */ |
| b.none 0b |
| |
| /* Found end-of-string or inequality. */ |
| 1: brkb p2.b, p0/z, p2.b /* find first such */ |
| lasta w0, p2, z0.b /* extract each char */ |
| lasta w1, p2, z1.b |
| sub x0, x0, x1 /* return comparison */ |
| ret |
| |
| /* First fault failed: only some of the vector is valid. |
| Perform the comparison only on the valid bytes. */ |
| 2: cmpeq p2.b, p1/z, z0.b, z1.b /* compare strings, as above */ |
| cmpne p3.b, p1/z, z0.b, 0 |
| nands p2.b, p1/z, p2.b, p3.b |
| b.any 1b |
| |
| /* No inequality or zero found. Re-init FFR, incr and loop. */ |
| setffr |
| incp x3, p1.b |
| b 0b |
| |
| /* Found end-of-count. */ |
| 9: mov x0, 0 /* return equal */ |
| ret |
| |
| END (__strncmp_aarch64_sve) |
| |
| #endif |
| |
| END_FILE |
