[cc65] MD5 checksum (ulongs really)

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From: Maciej Witkowiak (ytm_at_elysium.pl)
Date: 2003-08-19 16:14:17 

Well, all you people downloading ISOz on your 6502 machinez can check md5 sums
now :)

I didn't bother to write a full-featured md5sum program, just take a reference
implementation from RFC 1321, rewrite function headers and use cc65 on it.

The reason I write here about it is that one functions needs to be changed and
I don't know if it is or not cc65 bug or should I read the docs.

Here is the original code (UINT4 is unsigned long int):

static void Decode (UINT4 *output, unsigned char *input, unsigned int len) {
  unsigned int i, j;
  for (i = 0, j = 0; j < len; i++, j += 4)
     output[i] = ((UINT4)input[j]) | (((UINT4)input[j+1]) << 8) |
        (((UINT4)input[j+2]) << 16) | (((UINT4)input[j+3]) << 24);
 }

It doesn't work correctly.
Here is a version that works:

static void Decode (UINT4 *output, unsigned char *input, unsigned int len) {
  unsigned int i, j;
  union { char tab[4];
          UINT4 tabl; } uni;
  for (i = 0, j = 0; j < len; i++, j += 4) {
      uni.tab[0]=input[j];   uni.tab[1]=input[j+1];
      uni.tab[2]=input[j+2]; uni.tab[3]=input[j+3];
      output[i]=uni.tabl;
   }
  }

There's more:

#define UINT4 unsigned long int
unsigned char input[4];
UINT4 output[1];

void foo(void) {
  unsigned int i,j;

  output[0]=i=j=0;
  input[0]=0x01; input[1]=0x02; input[2]=0x03; input[3]=0x04;

  output[i] = ((UINT4)input[j]) | (((UINT4)input[j+1]) << 8) |
   (((UINT4)input[j+2]) << 16) | (((UINT4)input[j+3]) << 24);
  printf("%lu ",output[i]);
  output[i] = (UINT4)input[j];
  printf("%lu ",output[i]);

 }

With gcc I get:
67305985 1
With cc65 (CVS HEAD, with and without -Osir) I get:
3048407553 65537

ytm

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