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fundamental: add ABS_DIFF macro

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Sometimes we want need to diff two unsigned numbers, which is awkward
because we need to cast them to something with a sign first, if we want
to use abs(). Let's add a helper that avoids the function call
altogether.

Also drop unnecessary parens arounds args which are delimited by commas.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
2026-04-11 14:58:34 +02:00
parent c9defc1beb
commit efbd8a26d6
2 changed files with 21 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/fundamental/macro-fundamental.h
+14 -6
View File
@@ -171,7 +171,7 @@
#define U64_GB (UINT64_C(1024) * U64_MB)
#undef MAX
#define MAX(a, b) __MAX(UNIQ, (a), UNIQ, (b))
#define MAX(a, b) __MAX(UNIQ, a, UNIQ, b)
#define __MAX(aq, a, bq, b) \
({ \
const typeof(a) UNIQ_T(A, aq) = (a); \
@@ -234,7 +234,7 @@ assert_cc(sizeof(long long) == sizeof(intmax_t));
})
#undef MIN
#define MIN(a, b) __MIN(UNIQ, (a), UNIQ, (b))
#define MIN(a, b) __MIN(UNIQ, a, UNIQ, b)
#define __MIN(aq, a, bq, b) \
({ \
const typeof(a) UNIQ_T(A, aq) = (a); \
@@ -242,6 +242,14 @@ assert_cc(sizeof(long long) == sizeof(intmax_t));
UNIQ_T(A, aq) < UNIQ_T(B, bq) ? UNIQ_T(A, aq) : UNIQ_T(B, bq); \
})
#define ABS_DIFF(a, b) __ABS_DIFF(UNIQ, a, UNIQ, b)
#define __ABS_DIFF(aq, a, bq, b) \
({ \
const typeof(a) UNIQ_T(A, aq) = (a); \
const typeof(b) UNIQ_T(B, bq) = (b); \
UNIQ_T(A, aq) < UNIQ_T(B, bq) ? UNIQ_T(B, bq) - UNIQ_T(A, aq) : UNIQ_T(A, aq) - UNIQ_T(B, bq); \
})
/* evaluates to (void) if _A or _B are not constant or of different types */
#define CONST_MIN(_A, _B) \
(__builtin_choose_expr( \
@@ -312,7 +320,7 @@ assert_cc(sizeof(long long) == sizeof(intmax_t));
})
#undef CLAMP
#define CLAMP(x, low, high) __CLAMP(UNIQ, (x), UNIQ, (low), UNIQ, (high))
#define CLAMP(x, low, high) __CLAMP(UNIQ, x, UNIQ, low, UNIQ, high)
#define __CLAMP(xq, x, lowq, low, highq, high) \
({ \
const typeof(x) UNIQ_T(X, xq) = (x); \
@@ -329,7 +337,7 @@ assert_cc(sizeof(long long) == sizeof(intmax_t));
* computation should be possible in the given type. Therefore, we use
* [x / y + !!(x % y)]. Note that on "Real CPUs" a division returns both the
* quotient and the remainder, so both should be equally fast. */
#define DIV_ROUND_UP(x, y) __DIV_ROUND_UP(UNIQ, (x), UNIQ, (y))
#define DIV_ROUND_UP(x, y) __DIV_ROUND_UP(UNIQ, x, UNIQ, y)
#define __DIV_ROUND_UP(xq, x, yq, y) \
({ \
const typeof(x) UNIQ_T(X, xq) = (x); \
@@ -341,11 +349,11 @@ assert_cc(sizeof(long long) == sizeof(intmax_t));
#define __ROUND_UP(q, x, y) \
({ \
const typeof(y) UNIQ_T(A, q) = (y); \
const typeof(x) UNIQ_T(B, q) = DIV_ROUND_UP((x), UNIQ_T(A, q)); \
const typeof(x) UNIQ_T(B, q) = DIV_ROUND_UP(x, UNIQ_T(A, q)); \
typeof(x) UNIQ_T(C, q); \
MUL_SAFE(&UNIQ_T(C, q), UNIQ_T(B, q), UNIQ_T(A, q)) ? UNIQ_T(C, q) : (typeof(x)) -1; \
})
#define ROUND_UP(x, y) __ROUND_UP(UNIQ, (x), (y))
#define ROUND_UP(x, y) __ROUND_UP(UNIQ, x, y)
#define CASE_F_1(X) case X:
#define CASE_F_2(X, ...) case X: CASE_F_1( __VA_ARGS__)
src/test/test-macro.c
+7
View File
@@ -130,6 +130,13 @@ TEST(MAX) {
assert_se(CLAMP(CLAMP(0, -10, 10), CLAMP(-5, 10, 20), CLAMP(100, -5, 20)) == 10);
}
TEST(ABS_DIFF) {
ASSERT_EQ(ABS_DIFF(5, 3), 2);
ASSERT_EQ(ABS_DIFF(3, 5), 2);
ASSERT_EQ(ABS_DIFF(5llu, 2llu), 3llu);
ASSERT_EQ(ABS_DIFF(3llu, 5llu), 2llu);
}
#pragma GCC diagnostic push
#ifdef __clang__
# pragma GCC diagnostic ignored "-Waddress-of-packed-member"