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Unaffect type 8, m1, bit 4 for MakeIndustry #6235

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DorpsGek opened this issue Feb 25, 2015 · 4 comments
Closed

Unaffect type 8, m1, bit 4 for MakeIndustry #6235

DorpsGek opened this issue Feb 25, 2015 · 4 comments
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flyspray This issue is imported from FlySpray (https://bugs.openttd.org/) patch from FlySpray This issue is in fact a Patch, but imported from FlySrpay

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@DorpsGek
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Samu opened the ticket and wrote:

This patch prevents MakeIndustry from setting m1 bit 4 to 0, by preserving it's extracted value.

According to both landscape and landscape grid documentation, I believe that bit location was free to be used and never touched for anything related to industry tiles. I discovered the issue when I was searching for free, unused bits. For me, it would be preferrible if that bit value was preserved, hence this patch.

Issue:
MakeIndustry in industry_map.h is setting all bit values for m1 to 0

Refer:
http://hg.openttd.org/openttd/trunk.hg/file/53f10edbd7f1/src/industry_map.h# l283
http://hg.openttd.org/openttd/trunk.hg/raw-file/53f10edbd7f1/docs/landscape.html
http://hg.openttd.org/openttd/trunk.hg/raw-file/53f10edbd7f1/docs/landscape_grid.html

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Reported version: 1.5.0-beta1
Operating system: All

This issue was imported from FlySpray: https://bugs.openttd.org/task/6235
@DorpsGek
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Samu wrote:

I'm sorry, this patch is introducing a "bug".

Upon loading an old save game, the old bit 4 information is not being converted to the new bit 4 information. It affects all Industries.

I intend to fix that.

This comment was imported from FlySpray: https://bugs.openttd.org/task/6235#comment13783

@DorpsGek
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Alberth wrote:

You cannot have a bit that is both free to use and never touched.

A bit 'free to use' means its use can start at any time. As such, you cannot use it for any purpose, and preserving the bit is useless (no-one cares what the value is anyway).
A bit 'never to touch' means it effectively has a use, but it is not documented.

Unused bits can be changed at will. When it gets a use, all code will be checked to do the right thing for the bit.

This comment was imported from FlySpray: https://bugs.openttd.org/task/6235#comment13784

@DorpsGek
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Samu wrote:

This version converts the old bit 4 information, as well as preserving the bit value that is also inadvertently modified during a DoCommand, just before MakeIndustry.

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This comment was imported from FlySpray: https://bugs.openttd.org/task/6235#comment13789

@DorpsGek
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peter1138 closed the ticket.

Reason for closing: Invalid

Incorrect assumptions about map array

This comment was imported from FlySpray: https://bugs.openttd.org/task/6235

@DorpsGek DorpsGek added Core flyspray This issue is imported from FlySpray (https://bugs.openttd.org/) patch from FlySpray This issue is in fact a Patch, but imported from FlySrpay labels Apr 7, 2018
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