stt: adjust naming to Google-style (excluding method names)

[openroad-ci]

Summary

adjust naming to Google-style (excluding method names)

Type of Change

• Refactoring

Impact

None

Verification

• I have verified that the local build succeeds (./etc/Build.sh).
• I have run the relevant tests and they pass.
• My code follows the repository's formatting guidelines.
• I have signed my commits (DCO).

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[gemini-code-assist]

Code Review

This pull request updates variable and constant naming across the stt module to improve consistency and better align with standard C++ naming conventions, such as using kPascalCase for constants and trailing underscores for member variables. The review feedback suggests further refining the names in src/stt/src/flt/flute.cpp by removing redundant wl suffixes from several constants and variables to ensure uniform naming throughout the file.

[gemini-code-assist]

To improve consistency with flutes_medium_degree and better adhere to the Google C++ Style Guide, consider using kAa, kBb, cc, and dd instead of the wl-suffixed names. This also avoids the lack of underscores in ccwl and ddwl (which should be cc_wl and dd_wl if the suffix is kept) and ensures tunable parameters are defined as named constants.

Suggested change

	constexpr double kAawl = 0.6;
	constexpr double kBbwl = 0.3;
	const float ccwl = 7.4 / ((d + 10.) * (d - 3.));
	const float ddwl = 4.8 / (d - 1);
	constexpr double kAa = 0.6;
	constexpr double kBb = 0.3;
	const float cc = 7.4 / ((d + 10.) * (d - 3.));
	const float dd = 4.8 / (d - 1);

References

1. Variables should use snake_case and constants should use kPascalCase. Consistency across similar functions is also a key maintainability principle. ^(link)
2. Define tunable parameters as named constants instead of using hardcoded magic numbers.

[gemini-code-assist]

Update usages of ccwl to cc for consistency.

Suggested change

	const float dx = ccwl * (xs[d - 2] - xs[1]);
	const float dy = ccwl * (ys[d - 2] - ys[1]);
	const float dx = cc * (xs[d - 2] - xs[1]);
	const float dy = cc * (ys[d - 2] - ys[1]);

[gemini-code-assist]

Update usages of kAawl and ddwl to kAa and dd for consistency.

Suggested change

	- kAawl * (ys[d - 2] - ys[1]) - ddwl * disty[r];
	- kAa * (ys[d - 2] - ys[1]) - dd * disty[r];

[gemini-code-assist]

Update usages of kBbwl and ddwl to kBb and dd for consistency.

Suggested change

	- kBbwl * (ys[si[r] + 1] - ys[si[r] - 1]) - ddwl * disty[r];
	- kBb * (ys[si[r] + 1] - ys[si[r] - 1]) - dd * disty[r];

[gemini-code-assist]

Update usages of kAawl and ddwl to kAa and dd for consistency.

Suggested change

	- kAawl * (xs[d - 2] - xs[1]) - ddwl * distx[r];
	- kAa * (xs[d - 2] - xs[1]) - dd * distx[r];

[gemini-code-assist]

Update usages of kBbwl and ddwl to kBb and dd for consistency.

Suggested change

	- kBbwl * (xs[s[r] + 1] - xs[s[r] - 1]) - ddwl * distx[r];
	- kBb * (xs[s[r] + 1] - xs[s[r] - 1]) - dd * distx[r];