Fixed bug #46
authorSam Lantinga
Tue, 14 Mar 2006 05:34:39 +0000
changeset 152438a12fd1a2c1
parent 1523 21b1fbb53f4a
child 1525 23a347cfbed8
Fixed bug #46

Date: Fri, 13 Jan 2006 18:09:45 -0500
From: mhall4400 vipmail kvcc edu
Subject: Possible SDL bug

Greetings

I believe Ive come across a bug in your SDL product (1.2.9), in the CD-ROM
control portion of the library.

When calling the SDL_CDPlay() function to play the last track of a CD using the
offset and length from an SDL_CD structure generated by SDL_CDOpen(), I get the
following error from a call to SDL_Error():

mciSendCommand() error: The specified parameter is out of range for the
specified command.

The code returning the error is:
SDL_CDPlay(g_playingDriveSDLCD,
g_playingDriveSDLCD->track[trackNumberInt].offset,
g_playingDriveSDLCD->track[trackNumberInt].length)

Subtracting one from the length of the provided length seems to repair the
problem:
SDL_CDPlay(g_playingDriveSDLCD,
g_playingDriveSDLCD->track[trackNumberInt].offset,
(g_playingDriveSDLCD->track[trackNumberInt].length) - 1)

Ive replicated this problem on Windows 98 SE (several months since last
patch), fully-patched Window ME, seldom-patched Windows XP SP1, and
fully-patched Windows XP SP2.

While investigating the issue, I came across a line in your librarys win32
source code in file \src\cdrom\win32\SDL_syscdrom.c (source code zip archive
from your download page), function: SDL_SYS_CDGetTOC(), line 226 where you add
1 to the value for length to fix MCI last track length bug. This may be the
source of the issue (because subtracting 1 from the length seems to resolve the
issue). Microsoft may have patched the referenced bug since you wrote that
line.

Mike Hall
src/cdrom/win32/SDL_syscdrom.c
     1.1 --- a/src/cdrom/win32/SDL_syscdrom.c	Tue Mar 14 04:00:03 2006 +0000
     1.2 +++ b/src/cdrom/win32/SDL_syscdrom.c	Tue Mar 14 05:34:39 2006 +0000
     1.3 @@ -216,8 +216,7 @@
     1.4  				cdrom->track[i - 1].length = MSF_TO_FRAMES(
     1.5  					MCI_MSF_MINUTE(mci_status.dwReturn),
     1.6  					MCI_MSF_SECOND(mci_status.dwReturn),
     1.7 -					MCI_MSF_FRAME(mci_status.dwReturn)) + 1; /* +1 to fix */
     1.8 -											/* MCI last track length bug */
     1.9 +					MCI_MSF_FRAME(mci_status.dwReturn));
    1.10  				/* compute lead-out offset */
    1.11  				cdrom->track[i].offset = cdrom->track[i - 1].offset +
    1.12  					cdrom->track[i - 1].length;