Enable large disk image support #2301

shermp · 2023-02-25T05:07:40Z

This PR enables large HDD disk images to be used with Dosbox-staging. It is similar to the large disk support in the fat32 testing branches, but I have taken a slightly different approach.

This PR does not implement IDE support for hard disks, nor does it enable FAT 32 support. It is sufficient to mount and boot large disk images using the -fs none option in imgmount.

@ThomasEricB you might be interested in testing this.

The results are in MB or sectors, and a uint32_t is large enough

ThomasEricB · 2023-02-25T12:04:27Z

Thank you @shermp ! I'll get to test it as soon as @kcgen reviews the code or creates a new branch!

Also add a 'cross_' prefix to the defines.

shermp · 2023-02-25T18:45:16Z

As suggested by @kcgen I have moved the fstream wrappers to cross.h so they can be used by more areas of dosbox in the future.

include/cross.h

src/dos/drive_fat.cpp

src/dos/program_imgmount.cpp

src/ints/bios_disk.cpp

kcgen · 2023-02-25T22:10:35Z

looks great, @shermp - only minor comments (and many repeating, so hopefully not too tedious).

Another thing I wanted to mention for the casts is that @FeralChild64 added some really nice clamp-to-type constexpr routines:

include/math_utils.h:constexpr int8_t clamp_to_int8(const T val)
include/math_utils.h:constexpr uint8_t clamp_to_uint8(const T val)
include/math_utils.h:constexpr int16_t clamp_to_int16(const T val)
include/math_utils.h:constexpr uint16_t clamp_to_uint16(const T val)
include/math_utils.h:constexpr int32_t clamp_to_int32(const T val)
include/math_utils.h:constexpr uint32_t clamp_to_uint32(const T val)

They're especially useful to prevent value wrap-around (if clamping is acceptable).

If both clamping and wrap-around are unacceptable, then check_cast<type> will catch out-of-bounds values in debug builds (which standard-cast won't), while being equal to a normal type-cast in release builds.

shermp · 2023-02-26T01:48:41Z

I've made some changes @kcgen , see what you think.

kcgen

Just minor bits and a a question.
Should be done after this round.
This is a big improvement @shermp , and provides very useful functions that can be used in many more places.

include/support.h

src/misc/support.cpp

src/dos/program_imgmount.cpp

src/misc/support.cpp

kcgen

If you can squash down the intermediate commits, that would tidy it up a bit.

Feel free to merge once you're happy w/ the last round (it should let you merge once it gets through CI and all discussions set to "resolved")

Add stdio file size functions Use stdio file size functions Use const auto Rename fstream_ functions to stdio_ Add missing return statement Remove divisor variables only used once The function names should be enough to explain the values Switch cast to int64_t Restore file position after finding size

shermp added 3 commits February 25, 2023 16:51

Add initial large file disk support

69f355d

Let imgmount mount large disk images

35b52a0

Cast disk image size calc result

d3a9543

The results are in MB or sectors, and a uint32_t is large enough

shermp requested a review from kcgen February 25, 2023 05:30

kcgen assigned shermp Feb 25, 2023

kcgen added the enhancement New feature or enhancement of existing features label Feb 25, 2023

Move large file wrappers to cross.h

4d14f07

Also add a 'cross_' prefix to the defines.