thepigeongenerator/coinflip
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create a macro to reduce the head strain of getting the width of a type

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Quinn
2025-06-20 00:26:56 +02:00
parent 29d76880e3
commit 210725ab52
1 changed files with 6 additions and 4 deletions
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10
src/main.c
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@@ -13,6 +13,8 @@
exit(ret); \ exit(ret); \
} while (0) } while (0)
#define WIDTHOF(x) (sizeof(x) * 8)
typedef unsigned long long ull; typedef unsigned long long ull;
typedef struct dynrdat { typedef struct dynrdat {
@@ -24,7 +26,7 @@ dynrdat* rdat = NULL;
static inline ull pow2_ceil(ull x) { static inline ull pow2_ceil(ull x) {
x -= !!x; // if x=0, remains 0; else x -= 1 x -= !!x; // if x=0, remains 0; else x -= 1
return 1ULL << ((sizeof(ull) * 8) - __builtin_clzll(x | 1)); return 1ULL << (WIDTHOF(ull) - __builtin_clzll(x | 1));
} }
static void quit(void) { static void quit(void) {
@@ -44,8 +46,8 @@ int main(int argc, char** argv) {
if (errno != 0) error(errno, "parse error for string: '%s'\n", argv[i]); if (errno != 0) error(errno, "parse error for string: '%s'\n", argv[i]);
// acquire random data (compiler will optimize MOD and DIV away since they're both base-2 constant values) // acquire random data (compiler will optimize MOD and DIV away since they're both base-2 constant values)
int mod = c % (sizeof(ull) * 8); // get the remainder of the available random bits int mod = c % WIDTHOF(ull); // get the remainder of the available random bits
c = c / (sizeof(ull) * 8); // compute our "word count" c = c / WIDTHOF(ull); // compute our "word count"
// dynamically scale the array to our needs, ensuring 2^n scaling // dynamically scale the array to our needs, ensuring 2^n scaling
size_t cap = pow2_ceil(c + !!mod); size_t cap = pow2_ceil(c + !!mod);
@@ -70,7 +72,7 @@ int main(int argc, char** argv) {
for (; n < (rdat->dat + c); n++) { for (; n < (rdat->dat + c); n++) {
int cnt = __builtin_popcountll(*n); // counts the set bits int cnt = __builtin_popcountll(*n); // counts the set bits
headsc += cnt; headsc += cnt;
tailsc += sizeof(ull) * 8 - cnt; tailsc += WIDTHOF(ull) - cnt;
} }
// if there is a remainder, use the last N to get this // if there is a remainder, use the last N to get this