The MASM Forum

Miscellaneous => 16 bit DOS Programming => Topic started by: Petra93 on November 20, 2015, 08:10:48 AM

Title: Problem with Function 3Fh
Post by: Petra93 on November 20, 2015, 08:10:48 AM
I am trying to read data from a 20 by 20 number array (Euler problem 11).  Each line in the array has spaces, CR and FF, for a total of 62 characters.
Thus I am trying to read 1240 characters initially.  The subsequent code removes the irrelevant characters and generates a 20 by 20 array of words
for further mathematical operations.  These 20-word lines are successfully created, until I try to read more than 610 bytes from the source.  The program
crashes when I ask it to read 620 bytes.  I have tried to use the extended-error function, in the debug mode, but any information I might have read
disappears when the program crashes.  Insights into this problem from anyone would be appreciated.

        xor    AX,AX      ;read data - function 3FH -
   mov   AH,3Fh      ;AX will be number of bytes read
   mov   BX,handla      
   mov   CX,620      ;for 10 lines - 62 per line
   mov   DX,offset buffa
   int   21h

   mov   AH,59h             ;extended error information
   mov   BX,00h
   int   21h
Title: Re: Problem with Function 3Fh
Post by: Petra93 on November 20, 2015, 09:12:31 AM
I have discovered, since my first post, that there was not enough room in the buffer to accommodate the
number of bytes I was trying to read.  That was the problem, and the program now runs as expected.

Thanks for looking at my problem.

Title: Re: Problem with Function 3Fh
Post by: dedndave on November 21, 2015, 03:48:54 AM
save yourself a lot of work....

Code: [Select]
abGrid db 08,02,22,97,38,15,00,40,00,75,04,05,07,78,52,12,50,77,91,08
       db 49,49,99,40,17,81,18,57,60,87,17,40,98,43,69,48,04,56,62,00
       db 81,49,31,73,55,79,14,29,93,71,40,67,53,88,30,03,49,13,36,65
       db 52,70,95,23,04,60,11,42,69,24,68,56,01,32,56,71,37,02,36,91
       db 22,31,16,71,51,67,63,89,41,92,36,54,22,40,40,28,66,33,13,80
       db 24,47,32,60,99,03,45,02,44,75,33,53,78,36,84,20,35,17,12,50
       db 32,98,81,28,64,23,67,10,26,38,40,67,59,54,70,66,18,38,64,70
       db 67,26,20,68,02,62,12,20,95,63,94,39,63,08,40,91,66,49,94,21
       db 24,55,58,05,66,73,99,26,97,17,78,78,96,83,14,88,34,89,63,72
       db 21,36,23,09,75,00,76,44,20,45,35,14,00,61,33,97,34,31,33,95
       db 78,17,53,28,22,75,31,67,15,94,03,80,04,62,16,14,09,53,56,92
       db 16,39,05,42,96,35,31,47,55,58,88,24,00,17,54,24,36,29,85,57
       db 86,56,00,48,35,71,89,07,05,44,44,37,44,60,21,58,51,54,17,58
       db 19,80,81,68,05,94,47,69,28,73,92,13,86,52,17,77,04,89,55,40
       db 04,52,08,83,97,35,99,16,07,97,57,32,16,26,26,79,33,27,98,66
       db 88,36,68,87,57,62,20,72,03,46,33,67,46,55,12,32,63,93,53,69
       db 04,42,16,73,38,25,39,11,24,94,72,18,08,46,29,32,40,62,76,36
       db 20,69,36,41,72,30,23,88,34,62,99,69,82,67,59,85,74,04,36,16
       db 20,73,35,29,78,31,90,01,74,31,49,71,48,86,81,16,23,57,05,54
       db 01,70,54,71,83,51,54,69,16,92,33,48,61,43,52,01,89,19,67,48