On 30 September 2010 02:41, Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net> wrote:

Replace sizeof("string")-1 with strlen("string")

We want to avoid calls to strlen at runtime if the string is already
known at compile time.
Turns out that gcc and clang will recognize constant strings and compute
the strlen result already at compile time, so trickery with sizeof only
reduces readability but does not improve the code.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>

Index: flashrom-const_strlen/processor_enable.c
===================================================================
--- flashrom-const_strlen/processor_enable.c (Revision 1183)
+++ flashrom-const_strlen/processor_enable.c (Arbeitskopie)
@@ -56,13 +56,13 @@
while (*ptr && isspace(*ptr))
ptr++;
/* "cpu" part appears only with some Linux versions. */
- if (strncmp(ptr, "cpu", sizeof("cpu") - 1) == 0)
- ptr += sizeof("cpu") - 1;
+ if (strncmp(ptr, "cpu", strlen("cpu")) == 0)
+ ptr += strlen("cpu");

if (strncmp ((const char *) ptr, (const char *) "cpu", 3) == 0)
      {
        ptr = ptr + 3;
      }

while (*ptr && isspace(*ptr))
ptr++;
- if (strncmp(ptr, "model", sizeof("model") - 1) != 0)
+ if (strncmp(ptr, "model", strlen("model")) != 0)
continue;
- ptr += sizeof("model") - 1;
+ ptr += strlen("model");

if (strncmp ((const char *) ptr, (const char *) "model", 5) != 0)
      {
        // predicted unlikely by continue predictor.;
        goto <D.4030>;
      }
    ptr = ptr + 5;

while (*ptr && isspace(*ptr))
ptr++;
if (*ptr != ':')
@@ -72,9 +72,9 @@
ptr++;
fclose(cpuinfo);
return (strncmp(ptr, "ICT Loongson-2 V0.3",
- sizeof("ICT Loongson-2 V0.3") - 1) == 0)
+ strlen("ICT Loongson-2 V0.3")) == 0)
|| (strncmp(ptr, "Godson2 V0.3 FPU V0.1",
- sizeof("Godson2 V0.3 FPU V0.1") - 1) == 0);
+ strlen("Godson2 V0.3 FPU V0.1")) == 0);
}

fclose (cpuinfo);
return strncmp ((const char *) ptr, (const char *) "ICT Loongson-2 V0.3", 19) == 0 || strncmp ((const char *) ptr, (const char *) "Godson2 V0.3 FPU V0.1", 22) == $
}

fclose(cpuinfo);
return 0;

--
http://www.hailfinger.org/

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