diff options
Diffstat (limited to 'libc/string/powerpc/memset.c')
| -rw-r--r-- | libc/string/powerpc/memset.c | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/libc/string/powerpc/memset.c b/libc/string/powerpc/memset.c new file mode 100644 index 000000000..c5903afa6 --- /dev/null +++ b/libc/string/powerpc/memset.c @@ -0,0 +1,81 @@ +/* + * Copyright (C) 2004 Joakim Tjernlund + * Copyright (C) 2000-2005 Erik Andersen <andersen@uclibc.org> + * + * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball. + */ + +/* These are carefully optimized mem*() functions for PPC written in C. + * Don't muck around with these function without checking the generated + * assmbler code. + * It is possible to optimize these significantly more by using specific + * data cache instructions(mainly dcbz). However that requires knownledge + * about the CPU's cache line size. + * + * BUG ALERT! + * The cache instructions on MPC8xx CPU's are buggy(they don't update + * the DAR register when causing a DTLB Miss/Error) and cannot be + * used on 8xx CPU's without a kernel patch to work around this + * problem. + */ + +#include <string.h> + +static inline int expand_byte_word(int c){ + /* this does: + c = c << 8 | c; + c = c << 16 | c ; + */ + asm("rlwimi %0,%0,8,16,23\n" + "\trlwimi %0,%0,16,0,15\n" + : "=r" (c) : "0" (c)); + return c; +} +void attribute_hidden *__memset(void *to, int c, size_t n) +{ + unsigned long rem, chunks; + unsigned char *tmp_to; + + chunks = n / 8; + tmp_to = to - 4; + c = expand_byte_word(c); + if (!chunks) + goto lessthan8; + rem = (unsigned long )tmp_to % 4; + if (rem) + goto align; + copy_chunks: + do { + *(unsigned long *)(tmp_to+4) = c; + tmp_to += 4; + *(unsigned long *)(tmp_to+4) = c; + tmp_to += 4; + } while (--chunks); + lessthan8: + n = n % 8; + if (n >= 4) { + *(unsigned long *)(tmp_to+4) = c; + tmp_to += 4; + n = n-4; + } + if (!n ) return to; + tmp_to += 3; + do { + *++tmp_to = c; + } while (--n); + + return to; + align: + rem = 4 - rem; + n = n-rem; + do { + *(tmp_to+4) = c; + ++tmp_to; + } while (--rem); + chunks = n / 8; + if (chunks) + goto copy_chunks; + goto lessthan8; +} + +strong_alias(__memset, memset) |