feat: cdma

cdma.Rmd

@@ -27,12 +27,21 @@ ASCII characters require 7 bits of information per character.
 ```{r input}
 lines <- readLines('./input.txt',encoding = 'ASCII')
 strToBin <- function(s){
-  # FIXME for strings longer than 1
   r <- as.integer(intToBits(utf8ToInt(s)))
   r <- r[1:7]
   return(r)
 }
-lines_bin <- do.call(rbind, lapply(lines, strToBin))
+
+lines_bin <- list()
+for (line in lines){
+  line_bin <- list()
+  for (char in   strsplit(line, "")[[1]]){
+    s <- strToBin(char)
+    line_bin <- append(line_bin, s)
+  }
+  lines_bin <- append(lines_bin, list(line_bin))
+}
+lines_bin <- do.call(rbind,lines_bin)
 ```
 
 ```{r input-demo, echo=FALSE}
@@ -63,7 +72,7 @@ for (j in 1:ncol(lines_bin)){
   col <- lines_bin[,j]
   output_symbol <- 0
   for (i in 1:length(col)){
-    symbol <- col[i] # the symbol to be encoded
+    symbol <- col[[i]] # the symbol to be encoded
     code <- orthogonals[i,] # the code vector
 
     single_symbol <- (-1)^(1+symbol) * code # the resulting encoded vector
@@ -97,19 +106,26 @@ decoded_m == lines_bin
 Then we apply our text encoding on each line separately, respecting the LSB/MSB order.
 ```{r text-decode}
 chunk <- function(x, chunk_size) {
-  split(x, cut(seq_along(x), breaks = 
+  chunks <- split(x, cut(seq_along(x), breaks = 
                  seq(0, length(x), by = chunk_size), include.lowest = TRUE))
+  lapply(chunks, as.list)
 }
+final <- c('','','','')
 for (i in 1:nrow(decoded_m)){
   line <- decoded_m[i,]
   symbols <- chunk(line, 7)
-  for (symbol in symbols){
-    binary_str <- paste(rev(symbol), collapse = "")
+  for (j in 1:length(symbols)){
+    binary_str <- paste(rev(symbols[[j]]), collapse = "")
     # Convert the binary string to a decimal value
     decimal <- strtoi(binary_str, base = 2)
     # Convert the decimal value to an ASCII character
     char <- intToUtf8(decimal)
-    print(char)
+    final[i] <- paste0(final[i], char)
   }
 }
+
+```
+
+```{r text-decode-demo, echo=FALSE}
+print(final)
 ```

input.txt

@@ -1,4 +1,4 @@
-a
-b
-c
-d
+da
+cb
+bc
+ad