On Sun, 8 Sep 2013, Nguyễn Thái Ngọc Duy wrote:
>
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclo...@gmail.com>
> ---
> pack-write.c | 29 +++++++++++++++++++++++++++++
> pack.h | 1 +
> 2 files changed, 30 insertions(+)
>
> diff --git a/pack-write.c b/pack-write.c
> index 88e4788..6f11104 100644
> --- a/pack-write.c
> +++ b/pack-write.c
> @@ -1,6 +1,7 @@
> #include "cache.h"
> #include "pack.h"
> #include "csum-file.h"
> +#include "varint.h"
>
> void reset_pack_idx_option(struct pack_idx_option *opts)
> {
> @@ -340,6 +341,34 @@ int encode_in_pack_object_header(enum object_type type,
> uintmax_t size, unsigned
> return n;
> }
>
> +/*
> + * The per-object header is a pretty dense thing, which is
> + * - first byte: low four bits are "size", then three bits of "type",
> + * and the high bit is "size continues".
> + * - each byte afterwards: low seven bits are size continuation,
> + * with the high bit being "size continues"
> + */
This comment is a bit misleading. It looks almost like the pack v2
object header encoding which is not a varint encoded value like this one
is.
> +int pv4_encode_in_pack_object_header(enum object_type type,
> + uintmax_t size, unsigned char *hdr)
Could we have a somewhat shorter function name?
pv4_encode_object_header() should be acceptable given "pv4" already
implies a pack.
> +{
> + uintmax_t val;
> + if (type < OBJ_COMMIT || type > OBJ_PV4_TREE || type == OBJ_OFS_DELTA)
> + die("bad type %d", type);
This test has holes, such as types 5 and 8.
I think this would be better as:
switch (type) {
case OBJ_COMMIT:
case OBJ_TREE:
case OBJ_BLOB:
case OBJ_TAG:
case OBJ_REF_DELTA:
case OBJ_PV4_COMMIT:
case OBJ_PV4_TREE:
break;
default:
die("bad type %d", type);
}
The compiler ought to be smart enough to optimize the contiguous case
range. And that makes it explicit and obvious what we test for.
> +
> + /*
> + * We allocate 4 bits in the LSB for the object type which
> + * should be good for quite a while, given that we effectively
> + * encodes only 5 object types: commit, tree, blob, delta,
> + * tag.
> + */
> + val = size;
> + if (MSB(val, 4))
> + die("fixme: the code doesn't currently cope with big sizes");
> + val <<= 4;
> + val |= type;
> + return encode_varint(val, hdr);
> +}
> +
> struct sha1file *create_tmp_packfile(char **pack_tmp_name)
> {
> char tmpname[PATH_MAX];
> diff --git a/pack.h b/pack.h
> index 855f6c6..38f869d 100644
> --- a/pack.h
> +++ b/pack.h
> @@ -83,6 +83,7 @@ extern off_t write_pack_header(struct sha1file *f, int,
> uint32_t);
> extern void fixup_pack_header_footer(int, unsigned char *, const char *,
> uint32_t, unsigned char *, off_t);
> extern char *index_pack_lockfile(int fd);
> extern int encode_in_pack_object_header(enum object_type, uintmax_t,
> unsigned char *);
> +extern int pv4_encode_in_pack_object_header(enum object_type, uintmax_t,
> unsigned char *);
>
> #define PH_ERROR_EOF (-1)
> #define PH_ERROR_PACK_SIGNATURE (-2)
> --
> 1.8.2.83.gc99314b
>
> --
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