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build system: finer-grained selection of search speedup table.

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KNOWN_APPNAME_OFFSETS=8 versus KNOWN_APPNAME_OFFSETS=0:

function                                             old     new   delta
find_applet_by_name                                   55     136     +81
applet_nameofs                                         -      14     +14
run_applet_and_exit                                  757     758      +1

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2016-04-02 15:18:26 +02:00
parent 9f2f96edfa
commit dd02a05e08
1 changed files with 33 additions and 32 deletions
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63
applets/applet_tables.c
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@ -58,41 +58,32 @@ static int str_isalnum_(const char *s)
return 1; return 1;
} }
// Before linear search, narrow it down by looking at N "equidistant" names:
// KNOWN_APPNAME_OFFSETS cycles code_size
// 0 9057
// 2 4604 +32
// 4 2407 +75
// 8 1342 +98
// 16 908 +130
// 32 884 +194
// With 8, applet_nameofs[] table has 7 elements.
#define KNOWN_APPNAME_OFFSETS 8
int main(int argc, char **argv) int main(int argc, char **argv)
{ {
int i, j; int i, j;
int ofs, offset[KNOWN_APPNAME_OFFSETS], index[KNOWN_APPNAME_OFFSETS];
// unsigned MAX_APPLET_NAME_LEN = 1; // In find_applet_by_name(), before linear search, narrow it down
// by looking at N "equidistant" names. With ~350 applets:
// KNOWN_APPNAME_OFFSETS cycles
// 0 9057
// 2 4604 + ~100 bytes of code
// 4 2407 + 4 bytes
// 8 1342 + 8 bytes
// 16 908 + 16 bytes
// 32 884 + 32 bytes
// With 8, int16_t applet_nameofs[] table has 7 elements.
int KNOWN_APPNAME_OFFSETS = 8;
// With 128 applets we do two linear searches, with 1..7 strcmp's in the first one
// and 1..16 strcmp's in the second. With 256 apps, second search does 1..32 strcmp's.
if (NUM_APPLETS < 128)
KNOWN_APPNAME_OFFSETS = 4;
if (NUM_APPLETS < 32)
KNOWN_APPNAME_OFFSETS = 0;
qsort(applets, NUM_APPLETS, sizeof(applets[0]), cmp_name); qsort(applets, NUM_APPLETS, sizeof(applets[0]), cmp_name);
for (i = 0; i < KNOWN_APPNAME_OFFSETS; i++)
index[i] = i * NUM_APPLETS / KNOWN_APPNAME_OFFSETS;
ofs = 0;
for (i = 0; i < NUM_APPLETS; i++) {
for (j = 0; j < KNOWN_APPNAME_OFFSETS; j++)
if (i == index[j])
offset[j] = ofs;
ofs += strlen(applets[i].name) + 1;
}
/* If the list of names is too long refuse to proceed */
if (ofs > 0xffff)
return 1;
if (!argv[1]) if (!argv[1])
return 1; return 1;
i = open(argv[1], O_WRONLY | O_TRUNC | O_CREAT, 0666); i = open(argv[1], O_WRONLY | O_TRUNC | O_CREAT, 0666);
if (i < 0) if (i < 0)
return 1; return 1;
@ -108,16 +99,26 @@ int main(int argc, char **argv)
printf("#define SINGLE_APPLET_MAIN %s_main\n", applets[0].main); printf("#define SINGLE_APPLET_MAIN %s_main\n", applets[0].main);
} }
if (KNOWN_APPNAME_OFFSETS > 0 && NUM_APPLETS > 2*KNOWN_APPNAME_OFFSETS) {
printf("#define KNOWN_APPNAME_OFFSETS %u\n\n", KNOWN_APPNAME_OFFSETS); printf("#define KNOWN_APPNAME_OFFSETS %u\n\n", KNOWN_APPNAME_OFFSETS);
if (KNOWN_APPNAME_OFFSETS > 0) {
int ofs, offset[KNOWN_APPNAME_OFFSETS], index[KNOWN_APPNAME_OFFSETS];
for (i = 0; i < KNOWN_APPNAME_OFFSETS; i++)
index[i] = i * NUM_APPLETS / KNOWN_APPNAME_OFFSETS;
ofs = 0;
for (i = 0; i < NUM_APPLETS; i++) {
for (j = 0; j < KNOWN_APPNAME_OFFSETS; j++)
if (i == index[j])
offset[j] = ofs;
ofs += strlen(applets[i].name) + 1;
}
/* If the list of names is too long refuse to proceed */
if (ofs > 0xffff)
return 1;
printf("const uint16_t applet_nameofs[] ALIGN2 = {\n"); printf("const uint16_t applet_nameofs[] ALIGN2 = {\n");
for (i = 1; i < KNOWN_APPNAME_OFFSETS; i++) for (i = 1; i < KNOWN_APPNAME_OFFSETS; i++)
printf("%d,\n", offset[i]); printf("%d,\n", offset[i]);
printf("};\n\n"); printf("};\n\n");
} }
else {
printf("#define KNOWN_APPNAME_OFFSETS 0\n\n");
}
//printf("#ifndef SKIP_definitions\n"); //printf("#ifndef SKIP_definitions\n");
printf("const char applet_names[] ALIGN1 = \"\"\n"); printf("const char applet_names[] ALIGN1 = \"\"\n");