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d2s_small_table.h: fix small table POW5_INV_OFFSETS #256

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Merged
ulfjack merged 1 commit into from
Jan 23, 2026
Merged

d2s_small_table.h: fix small table POW5_INV_OFFSETS #256

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8 changes: 6 additions & 2 deletions ryu/d2s_small_table.h
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,8 @@
#ifndef RYU_D2S_SMALL_TABLE_H
#define RYU_D2S_SMALL_TABLE_H

#include <assert.h>

// Defines HAS_UINT128 and uint128_t if applicable.
#include "ryu/d2s_intrinsics.h"

Expand All @@ -41,11 +43,11 @@ static const uint64_t DOUBLE_POW5_INV_SPLIT2[15][2] = {
{ 10313493231639821582u, 1313665730009899186u },
{ 12701016819766672773u, 2032799256770390445u }
};
static const uint32_t POW5_INV_OFFSETS[19] = {
static const uint32_t POW5_INV_OFFSETS[22] = {
0x54544554, 0x04055545, 0x10041000, 0x00400414, 0x40010000, 0x41155555,
0x00000454, 0x00010044, 0x40000000, 0x44000041, 0x50454450, 0x55550054,
0x51655554, 0x40004000, 0x01000001, 0x00010500, 0x51515411, 0x05555554,
0x00000000
0x50411500, 0x40040000, 0x05040110, 0x00000000
};

static const uint64_t DOUBLE_POW5_SPLIT2[13][2] = {
Expand Down Expand Up @@ -117,6 +119,7 @@ static inline void double_computeInvPow5(const uint32_t i, uint64_t* const resul
const uint128_t b0 = ((uint128_t) m) * (mul[0] - 1);
const uint128_t b2 = ((uint128_t) m) * mul[1]; // 1/5^base2 * 5^offset = 1/5^(base2-offset) = 1/5^i
const uint32_t delta = pow5bits(base2) - pow5bits(i);
assert(i / 16 < sizeof(POW5_INV_OFFSETS) / sizeof(POW5_INV_OFFSETS[0]));
const uint128_t shiftedSum =
((b0 >> delta) + (b2 << (64 - delta))) + 1 + ((POW5_INV_OFFSETS[i / 16] >> ((i % 16) << 1)) & 3);
result[0] = (uint64_t) shiftedSum;
Expand Down Expand Up @@ -173,6 +176,7 @@ static inline void double_computeInvPow5(const uint32_t i, uint64_t* const resul
}
// high1 | sum | low0
const uint32_t delta = pow5bits(base2) - pow5bits(i);
assert(i / 16 < sizeof(POW5_INV_OFFSETS) / sizeof(POW5_INV_OFFSETS[0]));
result[0] = shiftright128(low0, sum, delta) + 1 + ((POW5_INV_OFFSETS[i / 16] >> ((i % 16) << 1)) & 3);
result[1] = shiftright128(sum, high1, delta);
}
Expand Down