Looks good.
Ethan
On Tue, Jan 17, 2012 at 16:54, Ben Pfaff <b...@nicira.com> wrote:
> I might as well update this one too, so here's an incremental that
> updates a comment and adds a tests, followed by a replacement commit.
>
> diff --git a/lib/util.c b/lib/util.c
> index 694ba04..dfdc51e 100644
> --- a/lib/util.c
> +++ b/lib/util.c
> @@ -804,9 +804,13 @@ bitwise_copy(const void *src_, unsigned int src_len,
> unsigned int src_ofs,
> }
>
> /* Zeros the 'n_bits' bits starting from bit 'dst_ofs' in 'dst'. 'dst' is
> - * 'dst_len' bytes long. Bit 0 of 'dst' is the bit with value 1 in
> dst[dst_len
> - * - 1], bit 1 is the bit with value 2, bit 8 is the bit with value 1 in
> - * dst[dst_len - 2], and so on.
> + * 'dst_len' bytes long.
> + *
> + * If you consider all of 'dst' to be a single unsigned integer in network
> byte
> + * order, then bit N is the bit with value 2**N. That is, bit 0 is the bit
> + * with value 1 in dst[dst_len - 1], bit 1 is the bit with value 2, bit 2 is
> + * the bit with value 4, ..., bit 8 is the bit with value 1 in dst[dst_len -
> + * 2], and so on.
> *
> * Required invariant:
> * dst_ofs + n_bits <= dst_len * 8
> diff --git a/tests/test-util.c b/tests/test-util.c
> index 45ea8f2..82d0861 100644
> --- a/tests/test-util.c
> +++ b/tests/test-util.c
> @@ -102,6 +102,47 @@ check_bitwise_copy(void)
> }
> }
>
> +static void
> +check_bitwise_zero(void)
> +{
> + unsigned int n_loops;
> + int dst_ofs;
> + int n_bits;
> +
> + n_loops = 0;
> + for (n_bits = 0; n_bits <= 64; n_bits++) {
> + for (dst_ofs = 0; dst_ofs < 64 - n_bits; dst_ofs++) {
> + ovs_be64 dst = htonll(random_uint64());
> + ovs_be64 orig_dst = dst;
> + ovs_be64 expect;
> +
> + if (n_bits == 64) {
> + expect = htonll(0);
> + } else {
> + uint64_t mask = (UINT64_C(1) << n_bits) - 1;
> + expect = orig_dst & ~htonll(mask << dst_ofs);
> + }
> +
> + bitwise_zero(&dst, sizeof dst, dst_ofs, n_bits);
> + if (expect != dst) {
> + fprintf(stderr,"bitwise_zero(0x%016"PRIx64",8,%d, %d) "
> + "yielded 0x%016"PRIx64" "
> + "instead of the expected 0x%016"PRIx64"\n",
> + ntohll(orig_dst), dst_ofs,
> + n_bits,
> + ntohll(dst), ntohll(expect));
> + abort();
> + }
> +
> + n_loops++;
> + }
> + }
> +
> + if (n_loops != 64 * (64 + 1) / 2) {
> + abort();
> + }
> +}
> +
> int
> main(void)
> {
> @@ -127,5 +168,7 @@ main(void)
>
> check_bitwise_copy();
>
> + check_bitwise_zero();
> +
> return 0;
> }
>
> --8<--------------------------cut here-------------------------->8--
>
> From: Ben Pfaff <b...@nicira.com>
> Date: Tue, 17 Jan 2012 16:53:29 -0800
> Subject: [PATCH] util: New function bitwise_zero().
>
> Signed-off-by: Ben Pfaff <b...@nicira.com>
> ---
> lib/util.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
> lib/util.h | 4 +++-
> tests/test-util.c | 43 +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 94 insertions(+), 1 deletions(-)
>
> diff --git a/lib/util.c b/lib/util.c
> index 811902a..dfdc51e 100644
> --- a/lib/util.c
> +++ b/lib/util.c
> @@ -803,6 +803,54 @@ bitwise_copy(const void *src_, unsigned int src_len,
> unsigned int src_ofs,
> }
> }
>
> +/* Zeros the 'n_bits' bits starting from bit 'dst_ofs' in 'dst'. 'dst' is
> + * 'dst_len' bytes long.
> + *
> + * If you consider all of 'dst' to be a single unsigned integer in network
> byte
> + * order, then bit N is the bit with value 2**N. That is, bit 0 is the bit
> + * with value 1 in dst[dst_len - 1], bit 1 is the bit with value 2, bit 2 is
> + * the bit with value 4, ..., bit 8 is the bit with value 1 in dst[dst_len -
> + * 2], and so on.
> + *
> + * Required invariant:
> + * dst_ofs + n_bits <= dst_len * 8
> + */
> +void
> +bitwise_zero(void *dst_, unsigned int dst_len, unsigned dst_ofs,
> + unsigned int n_bits)
> +{
> + uint8_t *dst = dst_;
> +
> + if (!n_bits) {
> + return;
> + }
> +
> + dst += dst_len - (dst_ofs / 8 + 1);
> + dst_ofs %= 8;
> +
> + if (dst_ofs) {
> + unsigned int chunk = MIN(n_bits, 8 - dst_ofs);
> +
> + *dst &= ~(((1 << chunk) - 1) << dst_ofs);
> +
> + n_bits -= chunk;
> + if (!n_bits) {
> + return;
> + }
> +
> + dst--;
> + }
> +
> + while (n_bits >= 8) {
> + *dst-- = 0;
> + n_bits -= 8;
> + }
> +
> + if (n_bits) {
> + *dst &= ~((1 << n_bits) - 1);
> + }
> +}
> +
> /* Copies the 'n_bits' low-order bits of 'value' into the 'n_bits' bits
> * starting at bit 'dst_ofs' in 'dst', which is 'dst_len' bytes long.
> *
> diff --git a/lib/util.h b/lib/util.h
> index c8eb004..d504f2f 100644
> --- a/lib/util.h
> +++ b/lib/util.h
> @@ -1,5 +1,5 @@
> /*
> - * Copyright (c) 2008, 2009, 2010, 2011 Nicira Networks.
> + * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira Networks.
> *
> * Licensed under the Apache License, Version 2.0 (the "License");
> * you may not use this file except in compliance with the License.
> @@ -211,6 +211,8 @@ bool is_all_ones(const uint8_t *, size_t);
> void bitwise_copy(const void *src, unsigned int src_len, unsigned int
> src_ofs,
> void *dst, unsigned int dst_len, unsigned int dst_ofs,
> unsigned int n_bits);
> +void bitwise_zero(void *dst_, unsigned int dst_len, unsigned dst_ofs,
> + unsigned int n_bits);
> void bitwise_put(uint64_t value,
> void *dst, unsigned int dst_len, unsigned int dst_ofs,
> unsigned int n_bits);
> diff --git a/tests/test-util.c b/tests/test-util.c
> index 45ea8f2..82d0861 100644
> --- a/tests/test-util.c
> +++ b/tests/test-util.c
> @@ -102,6 +102,47 @@ check_bitwise_copy(void)
> }
> }
>
> +static void
> +check_bitwise_zero(void)
> +{
> + unsigned int n_loops;
> + int dst_ofs;
> + int n_bits;
> +
> + n_loops = 0;
> + for (n_bits = 0; n_bits <= 64; n_bits++) {
> + for (dst_ofs = 0; dst_ofs < 64 - n_bits; dst_ofs++) {
> + ovs_be64 dst = htonll(random_uint64());
> + ovs_be64 orig_dst = dst;
> + ovs_be64 expect;
> +
> + if (n_bits == 64) {
> + expect = htonll(0);
> + } else {
> + uint64_t mask = (UINT64_C(1) << n_bits) - 1;
> + expect = orig_dst & ~htonll(mask << dst_ofs);
> + }
> +
> + bitwise_zero(&dst, sizeof dst, dst_ofs, n_bits);
> + if (expect != dst) {
> + fprintf(stderr,"bitwise_zero(0x%016"PRIx64",8,%d, %d) "
> + "yielded 0x%016"PRIx64" "
> + "instead of the expected 0x%016"PRIx64"\n",
> + ntohll(orig_dst), dst_ofs,
> + n_bits,
> + ntohll(dst), ntohll(expect));
> + abort();
> + }
> +
> + n_loops++;
> + }
> + }
> +
> + if (n_loops != 64 * (64 + 1) / 2) {
> + abort();
> + }
> +}
> +
> int
> main(void)
> {
> @@ -127,5 +168,7 @@ main(void)
>
> check_bitwise_copy();
>
> + check_bitwise_zero();
> +
> return 0;
> }
> --
> 1.7.2.5
>
> _______________________________________________
> dev mailing list
> dev@openvswitch.org
> http://openvswitch.org/mailman/listinfo/dev
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