PCG64: algorithm fix and add support inc (sequence) parameter in constructor

Author: zeriyoshi

ext/random/random.c

@@ -467,15 +467,26 @@ static uint64_t pcg64_generate(void *state, bool *engine_unsafe) {
 	return result;
 }
 
+static void pcg64_seed_full(php_random_engine_state_pcg64 *state) {
+	random_uint128_t initstate, initseq;
+
+	initstate = state->s;
+	initseq = state->inc;
+
+	UINT128_CON(0ULL, 0ULL, state->s);
+	PCG64_ROTL1OR1(initseq, state->inc);
+	pcg64_step(state);
+	UINT128_ADD(initstate, state->s, state->s);
+	pcg64_step(state);
+}
+
 static void pcg64_seed(void *state, const uint64_t seed) {
 	php_random_engine_state_pcg64 *s = state;
-	random_uint128_t sd;
 
-	UINT128_CON(0ULL, seed, sd);
-	PCG64_ROTL1OR1(s->s, s->inc);
-	pcg64_step(s);
-	UINT128_ADD(sd, s->s, s->s);
-	pcg64_step(s);
+	UINT128_CON(0ULL, seed, s->s);
+	UINT128_CON(0ULL, 0ULL, s->inc);
+
+	pcg64_seed_full(s);
 }
 
 static int pcg64_serialize(void *state, HashTable *data) {
@@ -1413,17 +1424,37 @@ PHP_METHOD(Random_Engine_PCG64, __construct)
 {
 	php_random_engine *engine = Z_RANDOM_ENGINE_P(ZEND_THIS);
 	php_random_engine_state_pcg64 *state = engine->state;
-	zend_string *str_seed = NULL;
-	zend_long int_seed = 0;
+	zend_string *str_seed = NULL, *str_seq = NULL;
+	zend_long int_seed = 0, int_seq = 0;
 	bool seed_is_null = true;
 	int i, j;
 	uint64_t t[2];
 
-	ZEND_PARSE_PARAMETERS_START(0, 1)
+	ZEND_PARSE_PARAMETERS_START(0, 2)
 		Z_PARAM_OPTIONAL;
 		Z_PARAM_STR_OR_LONG_OR_NULL(str_seed, int_seed, seed_is_null);
+		Z_PARAM_STR_OR_LONG(str_seq, int_seq);
 	ZEND_PARSE_PARAMETERS_END();
 
+	if (str_seq) {
+		/* char (8 bit) * 16 = 128 bits */
+		if (ZSTR_LEN(str_seq) == 16) {
+			/* Endianness safe copy */
+			for (i = 0; i < 2; i++) {
+				t[i] = 0;
+				for (j = 0; j < 8; j++) {
+					t[i] += ((uint64_t) (unsigned char) ZSTR_VAL(str_seq)[(i * 8) + j]) << (j * 8);
+				}
+			}
+			UINT128_CON(t[0], t[1], state->inc);
+		} else {
+			zend_argument_value_error(2, "sequence strings must be 16 bytes");
+			RETURN_THROWS();
+		}
+	} else {
+		UINT128_CON(0ULL, int_seq, state->inc);
+	}
+
 	if (seed_is_null) {
 		if (php_random_bytes_silent(&state->s, sizeof(random_uint128_t)) == FAILURE) {
 			zend_throw_exception(spl_ce_RuntimeException, "Random number generate failed", 0);
@@ -1441,14 +1472,15 @@ PHP_METHOD(Random_Engine_PCG64, __construct)
 					}
 				}
 				UINT128_CON(t[0], t[1], state->s);
-				UINT128_CON(0ULL, 0ULL, state->inc);
 			} else {
 				zend_argument_value_error(1, "state strings must be 16 bytes");
 				RETURN_THROWS();
 			}
 		} else {
-			engine->algo->seed(state, int_seed);
+			UINT128_CON(0ULL, int_seed, state->s);
 		}
+
+		pcg64_seed_full(state);
 	}
 }
 /* }}} */

ext/random/random.stub.php

@@ -59,7 +59,7 @@ public function __debugInfo(): array {}
 
     class PCG64 implements Random\SeedableEngine, Random\SerializableEngine
     {
-        public function __construct(string|int|null $seed = null) {}
+        public function __construct(string|int|null $seed = null, string|int $seequence = 0) {}
 
         /** @implementation-alias Random\Engine\CombinedLCG::generate */
         public function generate(): string {}

ext/random/random_arginfo.h

@@ -1,5 +1,5 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: 08434169eadaff969e4cd3b0c3c66b909f45fe81 */
+ * Stub hash: c1d50aee843582e2bebea3a515f47c28978a2a85 */
 
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_lcg_value, 0, 0, IS_DOUBLE, 0)
 ZEND_END_ARG_INFO()
@@ -63,6 +63,7 @@ ZEND_END_ARG_INFO()
 
 ZEND_BEGIN_ARG_INFO_EX(arginfo_class_Random_Engine_PCG64___construct, 0, 0, 0)
 	ZEND_ARG_TYPE_MASK(0, seed, MAY_BE_STRING|MAY_BE_LONG|MAY_BE_NULL, "null")
+	ZEND_ARG_TYPE_MASK(0, seequence, MAY_BE_STRING|MAY_BE_LONG, "0")
 ZEND_END_ARG_INFO()
 
 #define arginfo_class_Random_Engine_PCG64_generate arginfo_class_Random_Engine_CombinedLCG_generate

ext/random/tests/02_engine/pcg64_seed.phpt

@@ -31,17 +31,17 @@ for ($i = 0; $i < 1000; $i++) {
 --EXPECTF--
 Random\Engine\PCG64::__construct(): Argument #1 ($seed) must be of type string|int|null, float given
 Random\Engine\PCG64::__construct(): Argument #1 ($seed) state strings must be 16 bytes
-object(Random\Engine\PCG64)#%d (%d) {
+object(Random\Engine\PCG64)#%d (1) {
   ["__states"]=>
   array(4) {
     [0]=>
-    string(18) "578437695752307201"
+    string(19) "3130348909074048294"
     [1]=>
-    string(18) "578437695752307201"
+    string(20) "10673822082922804875"
     [2]=>
     string(1) "0"
     [3]=>
-    string(1) "0"
+    string(1) "1"
   }
 }
-string(16) "e68b42d3478fa786"
+string(16) "c372f38083fbb0bb"

ext/random/tests/02_engine/pcg64_value_with_inc.phpt

@@ -0,0 +1,17 @@
+--TEST--
+Random: Engine: PCG64: value with inc
+--FILE--
+<?php
+
+$engine = new \Random\Engine\PCG64(1234, 114514);
+
+for ($i = 0; $i < 10000; $i++) {
+    $engine->generate();
+}
+
+$engine->jump(1234567);
+
+echo \bin2hex($engine->generate());
+?>
+--EXPECT--
+9eac7778c37b81f0