library(sound)
dyn.load("steganography.so")

stegaBits <- function(sonido,bits=0,porcentaje=100,accion=0) {
# sonido: Sample a modificar
# bits: cantidad de bits menos significativos a modificar
# porcentaje: relación de la muestras que a modificar. Se distribuyen de manera uniforme.
# accion: 0riza (0), 1riza(1) o random(2).
# devuelve un Sample con las muestras en integer modificadas.
  return(as.Sample(.C("bits", sonido[["sound"]], length(sonido[["sound"]]),as.integer(bits),as.integer(porcentaje),as.integer(accion))[[1]],sonido$rate,sonido$bits))
}

loadSampleAsBits <- function(filename,filecheck=TRUE) {
#Copiado, con pequeñas modificaciones, de "sound,loadSample()"
  if (!is.null(class(filename)) && class(filename)=="Sample") return(filename)
  if (mode(filename)!="character")
    stop("Argument 'filename' must be a character string.")
  if (substr(filename,nchar(filename)-3,nchar(filename))!=".wav")
    stop("Filename must have the extension .wav.")
  if (filecheck){
    if (file.access(filename)==-1)
      stop("File not found.")
    if (file.access(filename,4)==-1)
      stop("No read permission for this file.")
  }

  fileR <- file(filename,"rb")

  if(readChar(fileR, nchars=4) != 'RIFF')
    stop("File is not RIFF format.")
  readBin(fileR, "integer", n = 4, size = 1)
  if(readChar(fileR, nchars=4) != 'WAVE')
    stop("File is not WAVE format.")

              readBin(fileR,"integer",n=10,size=1)
  channels <- readBin(fileR,"integer",     size=2, endian='little')
  rate     <- readBin(fileR,"integer",     size=4, endian='little')
              readBin(fileR,"integer",n= 6,size=1)
  bits     <- readBin(fileR,"integer",     size=2, endian='little')
              readBin(fileR,"integer",n= 4,size=1)
  Length   <- readBin(fileR,"integer",     size=4, endian='little')
  if (bits==8)
      data <- readBin(fileR,"integer",n=Length  ,size=1,signed=FALSE, endian='little')
  else
      data <- readBin(fileR,"integer",n=Length/2,size=2,signed=TRUE , endian='little')
  close(fileR)

  if (channels==2)
    dim(data) <- c(channels,length(data)/channels)

  return(as.Sample(data,rate,bits))
}


stegaSampleAsDouble <- function (sonido) {
  if (sonido$bits==8)
    sonido$sound   <- sonido$sound/128-1
  else
    sonido$sound   <- sonido$sound/32768
  return(sonido)
}

stegaSampleAsBits <- function (sonido) {
  canales=channels(sonido)
  if (sonido$bits==8)
    sonido$sound   <- as.integer((sonido$sound+1)*128)
  else
    sonido$sound   <- as.integer(sonido$sound*32768)

  if (canales==2)
    dim(sonido$sound) <- c(canales,length(sonido$sound)/canales)

  return(sonido)
}