From 0223e2faaebcb4065d9c37f55e8798196f911ae9 Mon Sep 17 00:00:00 2001
From: Mitya Selivanov <automainint@guattari.tech>
Date: Sun, 11 Dec 2022 23:46:56 +0100
Subject: [bigint] Big endian correctness
---
source/kit/bigint.h | 225 ++++++++++++++++++++----------------
source/test/unittests/bigint.test.c | 2 +-
2 files changed, 126 insertions(+), 101 deletions(-)
(limited to 'source')
diff --git a/source/kit/bigint.h b/source/kit/bigint.h
index 30233c6..7bb6a24 100644
--- a/source/kit/bigint.h
+++ b/source/kit/bigint.h
@@ -13,9 +13,6 @@ extern "C" {
# define KIT_BIGINT_SIZE 64
#endif
-#define KIT_UWORD_MAX ((uint_fast32_t) -1)
-#define KIT_UWORD_SIZE sizeof(uint_fast32_t)
-
static_assert(sizeof(uint8_t) == 1, "uint8_t size should be 1 byte");
static_assert(sizeof(uint32_t) == 4,
"uint32_t size should be 4 bytes");
@@ -25,24 +22,10 @@ static_assert(KIT_BIGINT_SIZE > 0 && (KIT_BIGINT_SIZE % 8) == 0,
"Invalid big integer size");
typedef struct {
- union {
- struct {
- uint8_t v8[KIT_BIGINT_SIZE];
- };
- struct {
- uint32_t v32[KIT_BIGINT_SIZE / 4];
- };
- struct {
- uint64_t v64[KIT_BIGINT_SIZE / 8];
- };
- struct {
- uint_fast32_t v[KIT_BIGINT_SIZE / KIT_UWORD_SIZE];
- };
- };
+ uint32_t v[KIT_BIGINT_SIZE / 4];
} kit_bigint_t;
-typedef uint_fast32_t kit_uword_t;
-typedef uint_fast8_t kit_bit_t;
+typedef uint_fast8_t kit_bit_t;
#ifdef __GNUC__
# pragma GCC diagnostic push
@@ -52,29 +35,29 @@ typedef uint_fast8_t kit_bit_t;
# pragma GCC optimize("O3")
#endif
-static kit_bigint_t kit_bi_uword(kit_uword_t const x) {
+static kit_bigint_t kit_bi_uint32(uint32_t const x) {
kit_bigint_t z;
- memset(z.v8, 0, KIT_BIGINT_SIZE);
+ memset(&z, 0, sizeof z);
z.v[0] = x;
return z;
}
static kit_bigint_t kit_bi_uint64(uint64_t const x) {
kit_bigint_t z;
- memset(z.v8, 0, KIT_BIGINT_SIZE);
- z.v64[0] = x;
+ memset(&z, 0, sizeof z);
+ z.v[0] = (uint32_t) (x & 0xffffffff);
+ z.v[1] = (uint32_t) (x >> 32);
return z;
}
static int kit_bi_equal(kit_bigint_t const x, kit_bigint_t const y) {
- return kit_ar_equal_bytes(1, KIT_BIGINT_SIZE, x.v8, 1,
- KIT_BIGINT_SIZE, y.v8);
+ return kit_ar_equal_bytes(1, KIT_BIGINT_SIZE, x.v, 1,
+ KIT_BIGINT_SIZE, y.v);
}
static int kit_bi_compare(kit_bigint_t const x,
kit_bigint_t const y) {
- for (ptrdiff_t i = KIT_BIGINT_SIZE / KIT_UWORD_SIZE - 1; i >= 0;
- i--)
+ for (ptrdiff_t i = KIT_BIGINT_SIZE / 4 - 1; i >= 0; i--)
if (x.v[i] < y.v[i])
return -1;
else if (x.v[i] > y.v[i])
@@ -83,32 +66,56 @@ static int kit_bi_compare(kit_bigint_t const x,
}
static ptrdiff_t kit_bi_significant_bit_count(kit_bigint_t const x) {
- ptrdiff_t bytes = KIT_BIGINT_SIZE - 1;
+ ptrdiff_t n = KIT_BIGINT_SIZE / 4 - 1;
- while (bytes > 0 && x.v8[bytes] == 0) bytes--;
+ while (n > 0 && x.v[n] == 0) n--;
- uint8_t const byte = x.v8[bytes];
+ uint32_t const i32 = x.v[n];
- if (byte == 0)
+ if (i32 == 0)
return 0;
- ptrdiff_t const bits = (byte & 0x80) != 0 ? 8
- : (byte & 0x40) != 0 ? 7
- : (byte & 0x20) != 0 ? 6
- : (byte & 0x10) != 0 ? 5
- : (byte & 0x08) != 0 ? 4
- : (byte & 0x04) != 0 ? 3
- : (byte & 0x02) != 0 ? 2
- : 1;
-
- return bytes * 8 + bits;
+ ptrdiff_t const bits = (i32 & 0x80000000u) != 0 ? 32
+ : (i32 & 0x40000000u) != 0 ? 31
+ : (i32 & 0x20000000u) != 0 ? 30
+ : (i32 & 0x10000000u) != 0 ? 29
+ : (i32 & 0x8000000u) != 0 ? 28
+ : (i32 & 0x4000000u) != 0 ? 27
+ : (i32 & 0x2000000u) != 0 ? 26
+ : (i32 & 0x1000000u) != 0 ? 25
+ : (i32 & 0x800000u) != 0 ? 24
+ : (i32 & 0x400000u) != 0 ? 23
+ : (i32 & 0x200000u) != 0 ? 22
+ : (i32 & 0x100000u) != 0 ? 21
+ : (i32 & 0x80000u) != 0 ? 20
+ : (i32 & 0x40000u) != 0 ? 19
+ : (i32 & 0x20000u) != 0 ? 18
+ : (i32 & 0x10000u) != 0 ? 17
+ : (i32 & 0x8000u) != 0 ? 16
+ : (i32 & 0x4000u) != 0 ? 15
+ : (i32 & 0x2000u) != 0 ? 14
+ : (i32 & 0x1000u) != 0 ? 13
+ : (i32 & 0x800u) != 0 ? 12
+ : (i32 & 0x400u) != 0 ? 11
+ : (i32 & 0x200u) != 0 ? 10
+ : (i32 & 0x100u) != 0 ? 9
+ : (i32 & 0x80u) != 0 ? 8
+ : (i32 & 0x40u) != 0 ? 7
+ : (i32 & 0x20u) != 0 ? 6
+ : (i32 & 0x10u) != 0 ? 5
+ : (i32 & 0x08u) != 0 ? 4
+ : (i32 & 0x04u) != 0 ? 3
+ : (i32 & 0x02u) != 0 ? 2
+ : 1;
+
+ return n * 32 + bits;
}
static kit_bigint_t kit_bi_and(kit_bigint_t const x,
kit_bigint_t const y) {
kit_bigint_t z;
- for (ptrdiff_t i = 0; i < KIT_BIGINT_SIZE / KIT_UWORD_SIZE; i++)
+ for (ptrdiff_t i = 0; i < KIT_BIGINT_SIZE / 4; i++)
z.v[i] = x.v[i] & y.v[i];
return z;
@@ -118,7 +125,7 @@ static kit_bigint_t kit_bi_or(kit_bigint_t const x,
kit_bigint_t const y) {
kit_bigint_t z;
- for (ptrdiff_t i = 0; i < KIT_BIGINT_SIZE / KIT_UWORD_SIZE; i++)
+ for (ptrdiff_t i = 0; i < KIT_BIGINT_SIZE / 4; i++)
z.v[i] = x.v[i] | y.v[i];
return z;
@@ -128,54 +135,50 @@ static kit_bigint_t kit_bi_xor(kit_bigint_t const x,
kit_bigint_t const y) {
kit_bigint_t z;
- for (ptrdiff_t i = 0; i < KIT_BIGINT_SIZE / KIT_UWORD_SIZE; i++)
+ for (ptrdiff_t i = 0; i < KIT_BIGINT_SIZE / 4; i++)
z.v[i] = x.v[i] ^ y.v[i];
return z;
}
-static kit_bigint_t kit_bi_shl_uword(kit_bigint_t const x,
- kit_uword_t y) {
+static kit_bigint_t kit_bi_shl_uint(kit_bigint_t const x,
+ uint32_t const y) {
kit_bigint_t z;
- memset(z.v8, 0, KIT_BIGINT_SIZE);
+ memset(&z, 0, sizeof z);
- ptrdiff_t const words = (ptrdiff_t) (y / (8 * KIT_UWORD_SIZE));
- ptrdiff_t const bits = (ptrdiff_t) (y % (8 * KIT_UWORD_SIZE));
+ ptrdiff_t const words = (ptrdiff_t) (y / 32);
+ ptrdiff_t const bits = (ptrdiff_t) (y % 32);
- for (ptrdiff_t i = words; i < KIT_BIGINT_SIZE / KIT_UWORD_SIZE;
- i++) {
+ for (ptrdiff_t i = words; i < KIT_BIGINT_SIZE / 4; i++) {
z.v[i] |= x.v[i - words] << bits;
- if (bits != 0 && i + 1 < KIT_BIGINT_SIZE / KIT_UWORD_SIZE)
- z.v[i + 1] = x.v[i - words] >> (8 * KIT_UWORD_SIZE - bits);
+ if (bits != 0 && i + 1 < KIT_BIGINT_SIZE / 4)
+ z.v[i + 1] = x.v[i - words] >> (32 - bits);
}
return z;
}
-static kit_bigint_t kit_bi_shr_uword(kit_bigint_t const x,
- kit_uword_t y) {
+static kit_bigint_t kit_bi_shr_uint(kit_bigint_t const x,
+ uint32_t const y) {
kit_bigint_t z;
- memset(z.v8, 0, KIT_BIGINT_SIZE);
+ memset(&z, 0, sizeof z);
- ptrdiff_t const words = (ptrdiff_t) (y / (8 * KIT_UWORD_SIZE));
- ptrdiff_t const bits = (ptrdiff_t) (y % (8 * KIT_UWORD_SIZE));
+ ptrdiff_t const words = (ptrdiff_t) (y / 32);
+ ptrdiff_t const bits = (ptrdiff_t) (y % 32);
- for (ptrdiff_t i = KIT_BIGINT_SIZE / KIT_UWORD_SIZE - words - 1;
- i >= 0; i--) {
+ for (ptrdiff_t i = KIT_BIGINT_SIZE / 4 - words - 1; i >= 0; i--) {
z.v[i] |= x.v[i + words] >> bits;
if (bits != 0 && i > 0)
- z.v[i - 1] = x.v[i + words] << (8 * KIT_UWORD_SIZE - bits);
+ z.v[i - 1] = x.v[i + words] << (32 - bits);
}
return z;
}
-static kit_bit_t kit_bi_carry(kit_uword_t const x,
- kit_uword_t const y,
- kit_bit_t const carry) {
+static kit_bit_t kit_bi_carry(uint32_t const x, uint32_t const y,
+ kit_bit_t const carry) {
assert(carry == 0 || carry == 1);
- return KIT_UWORD_MAX - x < y || KIT_UWORD_MAX - x - y < carry ? 1
- : 0;
+ return 0xffffffffu - x < y || 0xffffffffu - x - y < carry ? 1 : 0;
}
static kit_bigint_t kit_bi_add(kit_bigint_t const x,
@@ -183,7 +186,7 @@ static kit_bigint_t kit_bi_add(kit_bigint_t const x,
kit_bigint_t z;
kit_bit_t carry = 0;
- for (ptrdiff_t i = 0; i < KIT_BIGINT_SIZE / KIT_UWORD_SIZE; i++) {
+ for (ptrdiff_t i = 0; i < KIT_BIGINT_SIZE / 4; i++) {
z.v[i] = x.v[i] + y.v[i] + carry;
carry = kit_bi_carry(x.v[i], y.v[i], carry);
}
@@ -195,9 +198,9 @@ static kit_bigint_t kit_bi_neg(kit_bigint_t const x) {
kit_bigint_t y;
kit_bit_t carry = 1;
- for (ptrdiff_t i = 0; i < KIT_BIGINT_SIZE / KIT_UWORD_SIZE; i++) {
- y.v[i] = (x.v[i] ^ KIT_UWORD_MAX) + carry;
- carry = kit_bi_carry(x.v[i] ^ KIT_UWORD_MAX, 0, carry);
+ for (ptrdiff_t i = 0; i < KIT_BIGINT_SIZE / 4; i++) {
+ y.v[i] = (x.v[i] ^ 0xffffffff) + carry;
+ carry = kit_bi_carry(x.v[i] ^ 0xffffffff, 0, carry);
}
return y;
@@ -208,9 +211,9 @@ static kit_bigint_t kit_bi_sub(kit_bigint_t const x,
kit_bigint_t z;
kit_bit_t carry = 1;
- for (ptrdiff_t i = 0; i < KIT_BIGINT_SIZE / KIT_UWORD_SIZE; i++) {
- z.v[i] = x.v[i] + (y.v[i] ^ KIT_UWORD_MAX) + carry;
- carry = kit_bi_carry(x.v[i], (y.v[i] ^ KIT_UWORD_MAX), carry);
+ for (ptrdiff_t i = 0; i < KIT_BIGINT_SIZE / 4; i++) {
+ z.v[i] = x.v[i] + (y.v[i] ^ 0xffffffff) + carry;
+ carry = kit_bi_carry(x.v[i], (y.v[i] ^ 0xffffffff), carry);
}
return z;
@@ -219,19 +222,19 @@ static kit_bigint_t kit_bi_sub(kit_bigint_t const x,
static kit_bigint_t kit_bi_mul_uint32(kit_bigint_t const x,
uint32_t const y) {
kit_bigint_t z;
- memset(z.v8, 0, KIT_BIGINT_SIZE);
+ memset(&z, 0, sizeof z);
if (y != 0)
for (ptrdiff_t i = 0; i < KIT_BIGINT_SIZE / 4; i++) {
- if (x.v32[i] == 0)
+ if (x.v[i] == 0)
continue;
- uint64_t carry = ((uint64_t) x.v32[i]) * ((uint64_t) y);
+ uint64_t carry = ((uint64_t) x.v[i]) * ((uint64_t) y);
for (ptrdiff_t k = i; k < KIT_BIGINT_SIZE / 4 && carry != 0;
k++) {
- uint64_t const sum = ((uint64_t) z.v32[k]) + carry;
- z.v32[k] = ((uint32_t) (sum & 0xffffffffull));
+ uint64_t const sum = ((uint64_t) z.v[k]) + carry;
+ z.v[k] = ((uint32_t) (sum & 0xffffffffull));
carry = sum >> 32;
}
}
@@ -242,22 +245,22 @@ static kit_bigint_t kit_bi_mul_uint32(kit_bigint_t const x,
static kit_bigint_t kit_bi_mul(kit_bigint_t const x,
kit_bigint_t const y) {
kit_bigint_t z;
- memset(z.v8, 0, KIT_BIGINT_SIZE);
+ memset(&z, 0, sizeof z);
for (ptrdiff_t i = 0; i < KIT_BIGINT_SIZE / 4; i++) {
- if (x.v32[i] == 0)
+ if (x.v[i] == 0)
continue;
for (ptrdiff_t j = 0; i + j < KIT_BIGINT_SIZE / 4; j++) {
- if (y.v32[j] == 0)
+ if (y.v[j] == 0)
continue;
- uint64_t carry = ((uint64_t) x.v32[i]) * ((uint64_t) y.v32[j]);
+ uint64_t carry = ((uint64_t) x.v[i]) * ((uint64_t) y.v[j]);
for (ptrdiff_t k = i + j; k < KIT_BIGINT_SIZE / 4 && carry != 0;
k++) {
- uint64_t const sum = ((uint64_t) z.v32[k]) + carry;
- z.v32[k] = ((uint32_t) (sum & 0xffffffffull));
+ uint64_t const sum = ((uint64_t) z.v[k]) + carry;
+ z.v[k] = ((uint32_t) (sum & 0xffffffffull));
carry = sum >> 32;
}
}
@@ -288,35 +291,55 @@ static kit_bi_division_t kit_bi_div(kit_bigint_t const x,
ptrdiff_t shift = x_bits - y_bits;
result.remainder = x;
- result.quotient = kit_bi_uword(0);
+ result.quotient = kit_bi_uint32(0);
- y = kit_bi_shl_uword(y, (kit_uword_t) shift);
+ y = kit_bi_shl_uint(y, (uint32_t) shift);
while (shift >= 0) {
if (kit_bi_compare(result.remainder, y) >= 0) {
result.remainder = kit_bi_sub(result.remainder, y);
- result.quotient.v8[shift / 8] |= (1u << (shift % 8));
+ result.quotient.v[shift / 32] |= (1u << (shift % 32));
}
- y = kit_bi_shr_uword(y, 1);
+ y = kit_bi_shr_uint(y, 1);
shift--;
}
return result;
}
+static void kit_bi_serialize(kit_bigint_t const in,
+ uint8_t *const out) {
+ for (ptrdiff_t i = 0; i < KIT_BIGINT_SIZE / 4; i++) {
+ out[i * 4] = (uint8_t) (in.v[i] & 0xff);
+ out[i * 4 + 1] = (uint8_t) ((in.v[i] >> 8) & 0xff);
+ out[i * 4 + 2] = (uint8_t) ((in.v[i] >> 16) & 0xff);
+ out[i * 4 + 3] = (uint8_t) ((in.v[i] >> 24) & 0xff);
+ }
+}
+
+static kit_bigint_t kit_bi_deserialize(uint8_t const *const in) {
+ kit_bigint_t out;
+ memset(&out, 0, sizeof out);
+
+ for (ptrdiff_t i = 0; i < KIT_BIGINT_SIZE; i++)
+ out.v[i / 4] |= ((uint32_t) in[i]) << (8 * (i % 4));
+
+ return out;
+}
+
static uint8_t kit_bin_digit(char const hex) {
return hex == '1' ? 1 : 0;
}
static kit_bigint_t kit_bi_bin(kit_str_t const bin) {
kit_bigint_t z;
- memset(z.v8, 0, KIT_BIGINT_SIZE);
+ memset(&z, 0, sizeof z);
for (ptrdiff_t i = 0; i < bin.size && i / 8 < KIT_BIGINT_SIZE;
i++) {
uint8_t const digit = kit_bin_digit(bin.values[bin.size - i - 1]);
- z.v8[i / 8] |= digit << (i % 8);
+ z.v[i / 32] |= digit << (i % 32);
}
return z;
@@ -327,8 +350,8 @@ static uint8_t kit_dec_digit(char const c) {
}
static kit_bigint_t kit_bi_dec(kit_str_t const dec) {
- kit_bigint_t z = kit_bi_uword(0);
- kit_bigint_t factor = kit_bi_uword(1);
+ kit_bigint_t z = kit_bi_uint32(0);
+ kit_bigint_t factor = kit_bi_uint32(1);
for (ptrdiff_t i = 0; i < dec.size; i++) {
uint32_t const digit = kit_dec_digit(
@@ -352,12 +375,12 @@ static uint8_t kit_hex_digit(char const hex) {
static kit_bigint_t kit_bi_hex(kit_str_t const hex) {
kit_bigint_t z;
- memset(z.v8, 0, KIT_BIGINT_SIZE);
+ memset(&z, 0, sizeof z);
for (ptrdiff_t i = 0; i < hex.size && i / 2 < KIT_BIGINT_SIZE;
i++) {
uint8_t const digit = kit_hex_digit(hex.values[hex.size - i - 1]);
- z.v8[i / 2] |= ((i % 2) == 0) ? digit : (digit << 4);
+ z.v[i / 8] |= digit << (8 * (i % 8));
}
return z;
@@ -381,11 +404,11 @@ static uint8_t kit_base32_digit(char const c) {
static kit_bigint_t kit_bi_base32(kit_str_t const base32) {
kit_bigint_t z;
- memset(z.v8, 0, KIT_BIGINT_SIZE);
+ memset(&z, 0, sizeof z);
for (ptrdiff_t i = 0; i < base32.size; i++) {
- z = kit_bi_shl_uword(z, 5 * i);
- z.v8[i] |= kit_base32_digit(base32.values[i]);
+ z = kit_bi_shl_uint(z, 5 * i);
+ z.v[0] |= kit_base32_digit(base32.values[i]);
}
return z;
@@ -413,8 +436,8 @@ static uint8_t kit_base58_digit(char const c) {
}
static kit_bigint_t kit_bi_base58(kit_str_t const base58) {
- kit_bigint_t z = kit_bi_uword(0);
- kit_bigint_t factor = kit_bi_uword(1);
+ kit_bigint_t z = kit_bi_uint32(0);
+ kit_bigint_t factor = kit_bi_uint32(1);
for (ptrdiff_t i = 0; i < base58.size; i++) {
uint32_t const digit = kit_base58_digit(
@@ -448,7 +471,7 @@ static kit_bigint_t kit_bi_base58(kit_str_t const base58) {
#ifndef KIT_DISABLE_SHORT_NAMES
# define bigint_t kit_bigint_t
-# define bi_uword kit_bi_uword
+# define bi_uint32 kit_bi_uint32
# define bi_uint64 kit_bi_uint64
# define bi_equal kit_bi_equal
# define bi_carry kit_bi_carry
@@ -457,6 +480,8 @@ static kit_bigint_t kit_bi_base58(kit_str_t const base58) {
# define bi_sub kit_bi_sub
# define bi_mul kit_bi_mul
# define bi_div kit_bi_div
+# define bi_serialize kit_bi_serialize
+# define bi_deserialize kit_bi_deserialize
# define hex_digit kit_hex_digit
# define bi_hex kit_bi_hex
# define bi_base58 kit_bi_base58
diff --git a/source/test/unittests/bigint.test.c b/source/test/unittests/bigint.test.c
index 66cd87a..5ca49b5 100644
--- a/source/test/unittests/bigint.test.c
+++ b/source/test/unittests/bigint.test.c
@@ -21,7 +21,7 @@ TEST("bigint hex sub") {
}
TEST("bigint base58") {
- REQUIRE(bi_equal(BASE58("31"), bi_uword(58 * 2)));
+ REQUIRE(bi_equal(BASE58("31"), bi_uint32(58 * 2)));
}
TEST("bigint base58 add") {
--
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