From f2f26136c1dd975a44feb98b93634e2c03d773b8 Mon Sep 17 00:00:00 2001
From: ugha <ugha>
Date: Mon, 12 Jul 2004 05:12:22 +0000
Subject: [PATCH] Minior cleanups -- removed commented out debugging code,
wrote better comments. (ugha)
---
core/c/src/jbigi.c | 74 +++++++++++++++++++++++++---------------------
1 file changed, 40 insertions(+), 34 deletions(-)
diff --git a/core/c/src/jbigi.c b/core/c/src/jbigi.c
index c134ecd65e..63ccbd2833 100644
--- a/core/c/src/jbigi.c
+++ b/core/c/src/jbigi.c
@@ -2,15 +2,12 @@
#include <gmp.h>
#include "jbigi.h"
-/********/
-//function prototypes
-
-//FIXME: should these go into jbigi.h? -- ughabugha
+/******** prototypes */
void convert_j2mp(JNIEnv* env, jbyteArray jvalue, mpz_t* mvalue);
void convert_mp2j(JNIEnv* env, mpz_t mvalue, jbyteArray* jvalue);
-/********/
+/******** nativeModPow() */
/*
* Class: net_i2p_util_NativeBigInteger
* Method: nativeModPow
@@ -27,47 +24,41 @@ void convert_mp2j(JNIEnv* env, mpz_t mvalue, jbyteArray* jvalue);
JNIEXPORT jbyteArray JNICALL Java_net_i2p_util_NativeBigInteger_nativeModPow
(JNIEnv* env, jclass cls, jbyteArray jbase, jbyteArray jexp, jbyteArray jmod) {
- // convert base, exponent, modulus into the format libgmp understands
- // call libgmp's modPow
- // convert libgmp's result into a big endian twos complement number
+ /* 1) Convert base, exponent, modulus into the format libgmp understands
+ * 2) Call libgmp's modPow.
+ * 3) Convert libgmp's result into a big endian twos complement number.
+ *
+ * Luckily we can use GMP's mpz_import() and mpz_export() functions.
+ */
mpz_t mbase;
mpz_t mexp;
mpz_t mmod;
- //mpz_t mresult;
jbyteArray jresult;
convert_j2mp(env, jbase, &mbase);
convert_j2mp(env, jexp, &mexp);
convert_j2mp(env, jmod, &mmod);
- //gmp_printf("mbase =%Zd\n", mbase);
- //gmp_printf("mexp =%Zd\n", mexp);
- //gmp_printf("mmod =%Zd\n", mmod);
-
+ /* Perform the actual powmod. We use mmod for the result because it is
+ * always at least as big as the result.
+ */
mpz_powm(mmod, mbase, mexp, mmod);
- //we use mod for the result because it is always at least as big
-
- //gmp_printf("mresult=%Zd\n", mmod);
convert_mp2j(env, mmod, &jresult);
- //convert_j2mp(env, jresult, &mresult);
-
- //gmp_printf("", mpz_cmp(mmod, mresult) == 0 ? "true" : "false");
mpz_clear(mbase);
mpz_clear(mexp);
mpz_clear(mmod);
- //mpz_clear(mresult);
return jresult;
}
-/********/
+/******** convert_j2mp() */
/*
* Initializes the GMP value with enough preallocated size, and converts the
- * Java value into the GMP value. The value that mvalue is pointint to
- * should be uninitialized
+ * Java value into the GMP value. The value that mvalue points to should be
+ * uninitialized
*/
void convert_j2mp(JNIEnv* env, jbyteArray jvalue, mpz_t* mvalue)
@@ -81,18 +72,29 @@ void convert_j2mp(JNIEnv* env, jbyteArray jvalue, mpz_t* mvalue)
mpz_init2(*mvalue, sizeof(jbyte) * 8 * size); //preallocate the size
/*
- * void mpz_import (mpz_t rop, size_t count, int order, int size, int endian, size_t nails, const void *op)
- * order = 1 - order can be 1 for most significant word first or -1 for least significant first.
- * endian = 1 - Within each word endian can be 1 for most significant byte first, -1 for least significant first
- * nails = 0 - The most significant nails bits of each word are skipped, this can be 0 to use the full words
+ * void mpz_import(
+ * mpz_t rop, size_t count, int order, int size, int endian,
+ * size_t nails, const void *op);
+ *
+ * order = 1
+ * order can be 1 for most significant word first or -1 for least
+ * significant first.
+ * endian = 1
+ * Within each word endian can be 1 for most significant byte first,
+ * -1 for least significant first.
+ * nails = 0
+ * The most significant nails bits of each word are skipped, this can
+ * be 0 to use the full words.
*/
mpz_import(*mvalue, size, 1, sizeof(jbyte), 1, 0, (void*)jbuffer);
(*env)->ReleaseByteArrayElements(env, jvalue, jbuffer, JNI_ABORT);
}
-/********/
+/******** convert_mp2j() */
/*
* Converts the GMP value into the Java value; Doesn't do anything else.
+ * Pads the resulting jbyte array with 0, so the twos complement value is always
+ * positive.
*/
void convert_mp2j(JNIEnv* env, mpz_t mvalue, jbyteArray* jvalue)
@@ -103,21 +105,25 @@ void convert_mp2j(JNIEnv* env, mpz_t mvalue, jbyteArray* jvalue)
copy = JNI_FALSE;
- size = (mpz_sizeinbase(mvalue, 2) + 7) / 8 + sizeof(jbyte); //+7 => ceil division
+ /* sizeinbase() + 7 => Ceil division */
+ size = (mpz_sizeinbase(mvalue, 2) + 7) / 8 + sizeof(jbyte);
*jvalue = (*env)->NewByteArray(env, size);
buffer = (*env)->GetByteArrayElements(env, *jvalue, ©);
- buffer[0] = 0;
+ buffer[0] = 0x00;
/*
- * void *mpz_export (void *rop, size_t *count, int order, int size, int endian, size_t nails, mpz_t op)
+ * void *mpz_export(
+ * void *rop, size_t *count, int order, int size,
+ * int endian, size_t nails, mpz_t op);
*/
mpz_export((void*)&buffer[1], &size, 1, sizeof(jbyte), 1, 0, mvalue);
+ /* mode has (supposedly) no effect if elems is not a copy of the
+ * elements in array
+ */
(*env)->ReleaseByteArrayElements(env, *jvalue, buffer, 0);
- //mode has (supposedly) no effect if elems is not a copy of the elements in array
}
-/********/
-
+/******** eof */
--
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