entropy.c File Reference

#include "entropy.h"
#include <stdlib.h>
#include <math.h>
#include <rz_util/rz_assert.h>

Go to the source code of this file.

Functions
bool	rz_entropy_init (RzEntropy *ctx)
bool	rz_entropy_update (RzEntropy *ctx, const ut8 *data, size_t len)
bool	rz_entropy_final (ut8 *digest, RzEntropy *ctx, bool fraction)

Function Documentation

rz_entropy_final()

bool rz_entropy_final	(	ut8 *	digest,
		RzEntropy *	ctx,
		bool	fraction
	)

Definition at line 24 of file entropy.c.

                                                                  {
    rz_return_val_if_fail(ctx && digest, false);
    double p, entropy = 0.0;
    ut64 count;
    for (size_t i = 0; i < 256; i++) {
        count = ctx->count[i];
        if (count) {
            p = ((double)count) / ctx->size;
            entropy -= p * log2(p);
        }
    }
    if (fraction && ctx->size) {
        entropy /= log2((double)RZ_MIN(ctx->size, 256));
    }
    rz_write_be_double(digest, entropy);
    return true;
}

References count, i, p, RZ_MIN, rz_return_val_if_fail, rz_write_be_double(), and ut64().

Referenced by plugin_entropy_final(), and plugin_entropy_small_block().

rz_entropy_init()

bool rz_entropy_init

(

RzEntropy *

ctx

)

Definition at line 9 of file entropy.c.

                                     {
    rz_return_val_if_fail(ctx, false);
    memset(ctx, 0, sizeof(RzEntropy));
    return true;
}

References memset(), and rz_return_val_if_fail.

Referenced by plugin_entropy_init(), and plugin_entropy_small_block().

rz_entropy_update()

bool rz_entropy_update	(	RzEntropy *	ctx,
		const ut8 *	data,
		size_t	len
	)

Definition at line 15 of file entropy.c.

                                                                    {
    rz_return_val_if_fail(ctx && data, false);
    for (size_t i = 0; i < len; i++) {
        ctx->count[data[i]]++;
    }
    ctx->size += len;
    return true;
}

References i, len, and rz_return_val_if_fail.

Referenced by plugin_entropy_small_block(), and plugin_entropy_update().