Messages in this thread |  | | | Date | Fri, 2 May 2008 17:30:30 -0700 | | From | Andrew Morton <> | | Subject | Re: [PATCH 12/12] net: use the common ascii hex helpers |
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On Fri, 02 May 2008 17:15:55 -0700 Harvey Harrison <harvey.harrison@gmail.com> wrote:
> int hex_char_to_int(char ch) > { > return -1 if not [a-fA-F0-9] > } > > int hex_to_u8(const char *buf, u8 *val) > int hex_to_u16(const char *buf, u16 *val) > int hex_to_u32(const char *buf, u32 *val) > int hex_to_u64(const char *buf, u64 *val) > > Which return the number of chars read and reads up to a maximum of > 2,4,8,16 chars respectively and returns early if a non-hex char > is encountered. > > Thoughts?
I dunno. Return-by-reference is a bit nasty and forces the compiler to generate extra code to put local storage into a stack slot rather than keeping it in a register.
Does anyone actually test whether hex_to_foo returns -1? Probably not many.
In which case it might be better to do
u64 hex_to_u64(const char *buf);
and, if we encounter a non-hex char, do a WARN_ON(1).
One could legitimately do
int c = hex_to_int(some_user_input); if (c < 0) { printk("user: you're an idiot\n"); } to perform validation and conversion in a single operation but I expect that such code is in the minority, and could be covered by running a separate
bool is_hex_string(const char *bug, size_t nchars);
beforehand?
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