yf13 commented on code in PR #20996:
URL: https://github.com/apache/nuttx/pull/20996#discussion_r4396097918
##########
include/nuttx/lib/math32.h:
##########
@@ -208,136 +208,135 @@ extern "C"
*/
# ifdef up_umul64_const
-# define umul64_const(res, m, n, bias) \
- (res) = up_umul64_const(m, n, bias)
+# define umul64_const(m, n, bias) up_umul64_const(m, n, bias)
# else
-# define umul64_const(res, m, n, bias) \
- do \
- { \
- uint32_t __m_lo = (m) & 0xffffffff; \
- uint32_t __m_hi = (m) >> 32; \
- uint32_t __n_lo = (n) & 0xffffffff; \
- uint32_t __n_hi = (n) >> 32; \
- uint32_t __res_lo; \
- uint32_t __res_hi; \
- uint32_t __tmp; \
- \
- if (!(bias)) \
- { \
- (res) = ((uint64_t)__m_lo * __n_lo) >> 32; \
- } \
- else if (!((m) & ((1ULL << 63) | (1ULL << 31)))) \
- { \
- (res) = ((m) + (uint64_t)__m_lo * __n_lo) >> 32; \
- } \
- else \
- { \
- (res) = (m) + (uint64_t)__m_lo * __n_lo; \
- __res_lo = (res) >> 32; \
- __res_hi = (__res_lo < __m_hi); \
- (res) = __res_lo | ((uint64_t)__res_hi << 32); \
- } \
- \
- if (!((m) & ((1ULL << 63) | (1ULL << 31)))) \
- { \
- (res) += (uint64_t)__m_lo * __n_hi; \
- (res) += (uint64_t)__m_hi * __n_lo; \
- (res) >>= 32; \
- } \
- else \
- { \
- (res) += (uint64_t)__m_lo * __n_hi; \
- __tmp = (res) >> 32; \
- (res) += (uint64_t)__m_hi * __n_lo; \
- __res_lo = (res) >> 32; \
- __res_hi = (__res_lo < __tmp); \
- (res) = __res_lo | ((uint64_t)__res_hi << 32); \
- } \
- \
- (res) += (uint64_t)__m_hi * __n_hi; \
- } \
- while (0)
+static inline_function uint64_t umul64_const(uint64_t m, uint64_t n,
+ int bias)
+{
+ uint32_t m_lo = (m) & 0xffffffff;
+ uint32_t m_hi = (m) >> 32;
+ uint32_t n_lo = (n) & 0xffffffff;
+ uint32_t n_hi = (n) >> 32;
+ uint32_t res_lo;
+ uint32_t res_hi;
+ uint32_t tmp;
+ uint64_t res;
+
+ if (!(bias))
+ {
+ res = ((uint64_t)m_lo * n_lo) >> 32;
+ }
+ else if (!((m) & ((1ULL << 63) | (1ULL << 31))))
+ {
+ res = ((m) + (uint64_t)m_lo * n_lo) >> 32;
+ }
+ else
+ {
+ res = (m) + (uint64_t)m_lo * n_lo;
+ res_lo = res >> 32;
+ res_hi = (res_lo < m_hi);
+ res = res_lo | ((uint64_t)res_hi << 32);
+ }
+
+ if (!((m) & ((1ULL << 63) | (1ULL << 31))))
+ {
+ res += (uint64_t)m_lo * n_hi;
+ res += (uint64_t)m_hi * n_lo;
+ res >>= 32;
+ }
+ else
+ {
+ res += (uint64_t)m_lo * n_hi;
+ tmp = res >> 32;
+ res += (uint64_t)m_hi * n_lo;
+ res_lo = res >> 32;
+ res_hi = (res_lo < tmp);
+ res = res_lo | ((uint64_t)res_hi << 32);
+ }
+
+ res += (uint64_t)m_hi * n_hi;
+
+ return res;
+}
# endif
-# define div64_const32(n, b) \
- do \
- { \
- uint64_t ___res; \
- uint64_t ___x; \
- uint64_t ___t; \
- uint64_t ___m; \
- uint64_t ___n = (n); \
- uint32_t ___p; \
- uint32_t ___bias; \
- uint32_t ___b = (b); \
- ___p = 1 << LOG2_FLOOR(___b); \
- ___m = (~0ULL / ___b) * ___p; \
- ___m += (((~0ULL % ___b + 1) * ___p) + ___b - 1) / ___b; \
- ___x = ~0ULL / ___b * ___b - 1; \
- ___res = ((___m & 0xffffffff) * (___x & 0xffffffff)) >> 32; \
- ___t = ___res += (___m & 0xffffffff) * (___x >> 32); \
- ___res += (___x & 0xffffffff) * (___m >> 32); \
- ___t = (___res < ___t) ? (1ULL << 32) : 0; \
- ___res = (___res >> 32) + ___t; \
- ___res += (___m >> 32) * (___x >> 32); \
- ___res /= ___p; \
- if (~0ULL % (___b / (___b & -___b)) == 0) \
- { \
- ___n /= (___b & -___b); \
- ___m = ~0ULL / (___b / (___b & -___b)); \
- ___p = 1; \
- ___bias = 1; \
- } \
- else if (___res != ___x / ___b) \
- { \
- ___bias = 1; \
- ___m = (~0ULL / ___b) * ___p; \
- ___m += ((~0ULL % ___b + 1) * ___p) / ___b; \
- } \
- else \
- { \
- uint32_t ___bits = -(___m & -___m); \
- ___bits |= ___m >> 32; \
- ___bits = (~___bits) << 1; \
- if (!___bits) \
- { \
- ___p /= (___m & -___m); \
- ___m /= (___m & -___m); \
- } \
- else \
- { \
- ___p >>= LOG2_FLOOR(___bits); \
- ___m >>= LOG2_FLOOR(___bits); \
- } \
- ___bias = 0; \
- } \
- umul64_const(___res, ___m, ___n, ___bias); \
- \
- ___res /= ___p; \
- (n) = ___res; \
- } \
- while (0)
-
-#if defined(CONFIG_HAVE_EXPRESSION_STATEMENT)
-# define div64_const(n, base) \
- ({ \
- uint64_t __n = (n); \
- uint32_t __base = (base); \
- if (IS_POWER_OF_2(__base)) \
- { \
- (__n) >>= LOG2_FLOOR(__base); \
- } \
- else if (UINTPTR_MAX == UINT32_MAX) \
- { \
- div64_const32(__n, __base); \
- } \
- else \
- { \
- __n /= __base; \
- } \
- __n; \
- })
+static inline_function uint64_t div64_const32(uint64_t n, uint32_t b)
+{
+ uint64_t res;
+ uint64_t x;
+ uint64_t t;
+ uint64_t m;
+ uint32_t p;
+ uint32_t bias;
+
+ p = 1 << LOG2_FLOOR(b);
+ m = (~0ULL / b) * p;
+ m += (((~0ULL % b + 1) * p) + b - 1) / b;
+ x = ~0ULL / b * b - 1;
+ res = ((m & 0xffffffff) * (x & 0xffffffff)) >> 32;
+ t = res += (m & 0xffffffff) * (x >> 32);
+ res += (x & 0xffffffff) * (m >> 32);
+ t = (res < t) ? (1ULL << 32) : 0;
+ res = (res >> 32) + t;
+ res += (m >> 32) * (x >> 32);
+ res /= p;
+
+ if (~0ULL % (b / (b & -b)) == 0)
+ {
+ n /= (b & -b);
+ m = ~0ULL / (b / (b & -b));
+ p = 1;
+ bias = 1;
+ }
+ else if (res != x / b)
+ {
+ bias = 1;
+ m = (~0ULL / b) * p;
+ m += ((~0ULL % b + 1) * p) / b;
+ }
+ else
+ {
+ uint32_t bits = -(m & -m);
+ bits |= m >> 32;
+ bits = (~bits) << 1;
+ if (!bits)
+ {
+ p /= (m & -m);
+ m /= (m & -m);
+ }
+ else
+ {
+ p >>= LOG2_FLOOR(bits);
+ m >>= LOG2_FLOOR(bits);
+ }
+
+ bias = 0;
+ }
+
+ res = umul64_const(m, n, bias);
+ res /= p;
+
+ return res;
+}
+#if defined(__GNUC__)
Review Comment:
@casaroli Thanks for the suggestion! but orginal `div_const()` and
`ltoa_invert` both drag 64bit div/mod funcs of libgcc on rv32, so keeping one
of them saves us nothing.
> CI shows flash overflows of up to 31 KB
I am wondering this is due to `inline func` isnt equivalent to original
macro form of `div_const` as said in comment of __div64_const32 macro of Linux
in include/asm-generic/div64.h:
```
* We rely on the fact that most of this code gets optimized \
* away at compile time due to constant propagation and only \
* a few multiplication instructions should remain. \
* Hence this monstrous macro (static inline doesn't always \
* do the trick here)
```
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