[cups.general] How to send jobs to a SCSI printer with cups?

[Mike Fedyk]

Mike Fedyk wrote:

> Mike Fedyk wrote:
>
>> Mike Fedyk wrote:
>>
>>> Is this right?
>>>
>>> In scsi-linux.c at line 185:
>>>
>>>      scsi_cmd[0] = 0x0a;       /* Group 0 print command */
>>>      scsi_cmd[1] = 0x00;
>>>      scsi_cmd[2] = bytes / 65536;
>>>      scsi_cmd[3] = bytes / 256;
>>>      scsi_cmd[4] = bytes;
>>>      scsi_cmd[5] = 0x00;
>>>
>>> According to [1], the format should be
>>>
>>> Operation code (0Ah)
>>> LUN
>>> MSB
>>> Transfer Length
>>> LSB
>>> Control
>>>
>>> I don't know if the linux scsi stack changes the orders of the 
>>> fields though...
>>>
>>> [1]
>>> http://www.danbbs.dk/~dino/SCSI/SCSI2-11.html
>>>
>> Here's a patch:
>> --- scsi-linux.c.orig   2004-09-10 16:14:08.000000000 -0700
>> +++ scsi-linux.c        2004-09-10 16:17:20.000000000 -0700
>> @@ -185,8 +185,8 @@
>>       scsi_cmd[0] = 0x0a;      /* Group 0 print command */
>>       scsi_cmd[1] = 0x00;
>>       scsi_cmd[2] = bytes / 65536;
>> -      scsi_cmd[3] = bytes / 256;
>> -      scsi_cmd[4] = bytes;
>> +      scsi_cmd[3] = bytes;
>> +      scsi_cmd[4] = bytes / 256;
>>       scsi_cmd[5] = 0x00;
>>
>>       for (try = 0; try < 10; try ++)
>>
>> ------------------------------------------------------------------------
>>
>> --- scsi-linux.c.orig    2004-09-10 16:14:08.000000000 -0700
>> +++ scsi-linux.c    2004-09-10 16:17:20.000000000 -0700
>> @@ -185,8 +185,8 @@
>>       scsi_cmd[0] = 0x0a;    /* Group 0 print command */
>>       scsi_cmd[1] = 0x00;
>>       scsi_cmd[2] = bytes / 65536;
>> -      scsi_cmd[3] = bytes / 256;
>> -      scsi_cmd[4] = bytes;
>> +      scsi_cmd[3] = bytes;
>> +      scsi_cmd[4] = bytes / 256;
>>       scsi_cmd[5] = 0x00;
>>
>>       for (try = 0; try < 10; try ++)
>>  
>>
> Well, if I did find a bug, it looks like this is the proper fix even 
> though the buffer size is only 8k bytes...
>
> --- scsi-linux.c.orig   2004-09-10 16:14:08.000000000 -0700
> +++ scsi-linux.c        2004-09-10 19:02:47.000000000 -0700
> @@ -184,9 +184,9 @@
>
>       scsi_cmd[0] = 0x0a;      /* Group 0 print command */
>       scsi_cmd[1] = 0x00;
> -      scsi_cmd[2] = bytes / 65536;
> -      scsi_cmd[3] = bytes / 256;
> -      scsi_cmd[4] = bytes;
> +      scsi_cmd[3] = bytes / 16777216;  /* High 8 bit value of 
> Transfer Lenght */
> +      scsi_cmd[2] = bytes / 65536;     /* Middle 8 bit value of 
> Transfer Lenght */
> +      scsi_cmd[4] = bytes / 256;       /* Low 8 bit value of Transfer 
> Lenght */
>       scsi_cmd[5] = 0x00;
>
>       for (try = 0; try < 10; try ++)
>
>------------------------------------------------------------------------
>
>--- scsi-linux.c.orig	2004-09-10 16:14:08.000000000 -0700
>+++ scsi-linux.c	2004-09-10 19:02:47.000000000 -0700
>@@ -184,9 +184,9 @@
>       
>       scsi_cmd[0] = 0x0a;	/* Group 0 print command */
>       scsi_cmd[1] = 0x00;
>-      scsi_cmd[2] = bytes / 65536;
>-      scsi_cmd[3] = bytes / 256;
>-      scsi_cmd[4] = bytes;
>+      scsi_cmd[3] = bytes / 16777216;	/* High 8 bit value of Transfer Lenght */
>+      scsi_cmd[2] = bytes / 65536;	/* Middle 8 bit value of Transfer Lenght */
>+      scsi_cmd[4] = bytes / 256;	/* Low 8 bit value of Transfer Lenght */
>       scsi_cmd[5] = 0x00;
> 
>       for (try = 0; try < 10; try ++)
>  
>
I knew something didn't feel right about that patch.

--- scsi-linux.c.orig   2004-09-10 16:14:08.000000000 -0700
+++ scsi-linux.c        2004-09-10 19:48:16.000000000 -0700
@@ -184,9 +184,9 @@

       scsi_cmd[0] = 0x0a;      /* Group 0 print command */
       scsi_cmd[1] = 0x00;
-      scsi_cmd[2] = bytes / 65536;
-      scsi_cmd[3] = bytes / 256;
-      scsi_cmd[4] = bytes;
+      scsi_cmd[3] = min(bytes / 65536, 256);   /* High 8 bit value of 
Transfer Lenght */
+      scsi_cmd[2] = min(bytes / 256, 256);     /* Middle 8 bit value of 
Transfer Lenght */
+      scsi_cmd[4] = min(bytes, 256);           /* Low 8 bit value of 
Transfer Lenght */
       scsi_cmd[5] = 0x00;

       for (try = 0; try < 10; try ++)

Since scsi_cmd is of type char, do I need the min() calls there, or will 
the values just be truncated to one char when you call a char as an array?
If you write an int to scsi_cmd[4] won't that write 4 or 8 bytes and 
thus overflow your char variable? 
Will min() write only 1 byte to a char if the value of an int is <= 256?
What file do I need to include for the min() function?

Yes, I'm new to C.  Can you tell? ;)

Mike