ci: 解消済み phpt を docker-phpt-tests の skip から除外し README を更新

方向系モードと bcdivmod の実装により、以下8件の公式 phpt テストが
拡張なし環境でも通るようになったため --skip から除外する:
bcdivmod, bcdivmod_by_zero, bcround_all, bcround_away_from_zero,
bcround_ceiling, bcround_floor, bcround_toward_zero, bcround_early_return

README には bcdivmod・全RoundingMode対応と、symfony/polyfill-php84
との共存挙動 (PHP 8.2/8.3 + 拡張ありでのオートロード順) を追記。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: nanasess

.github/workflows/ci.yml

@@ -98,7 +98,8 @@ jobs:
                   # scale_ini test skipped: bcmath.scale INI setting ignored without native extension
                   # gh20006 test skipped: requires BcMath\Number OOP API (not supported by polyfill)
                   # bcround_precision_bounds test skipped: requires BcMath\Number OOP API (not supported by polyfill)
-                  docker run --rm -v $PWD:/app bcmath-phpt-test:${{ matrix.php-version }} --skip bcdivmod,bug54598,bug72093,bug75178,gh15968,gh16262,scale_ini,bcmul_check_overflow,bug78878,bcpow_error1,bcpow_error2,bcpow_error3,bcpowmod_error,bcpowmod_with_mod_1,bcpowmod_zero_modulus,bcround_all,bcround_away_from_zero,bcround_ceiling,bcround_early_return,bcround_floor,bcround_toward_zero,bcscale_variation003,bcdivmod_by_zero,gh20006,bcround_precision_bounds
+                  # bcround directional modes + bcdivmod are now implemented, so those phpt tests no longer need skipping.
+                  docker run --rm -v $PWD:/app bcmath-phpt-test:${{ matrix.php-version }} --skip bug54598,bug72093,bug75178,gh15968,gh16262,scale_ini,bcmul_check_overflow,bug78878,bcpow_error1,bcpow_error2,bcpow_error3,bcpowmod_error,bcpowmod_with_mod_1,bcpowmod_zero_modulus,bcscale_variation003,gh20006,bcround_precision_bounds
         strategy:
             fail-fast: false
             matrix:

README.md

@@ -17,7 +17,7 @@
 ## 🚀 Features
 
 - ✅ Complete bcmath extension polyfill for PHP 8.1+
-- ✅ Supports all PHP 8.4+ bcmath functions including `bcfloor()`, `bcceil()`, and `bcround()`
+- ✅ Supports all PHP 8.4+ bcmath functions including `bcfloor()`, `bcceil()`, `bcround()`, and `bcdivmod()`
 - ✅ PHP 8.5 compatibility tested and verified
 - ✅ Zero dependencies in production (uses phpseclib for arbitrary precision math)
 - ✅ Seamless fallback when bcmath extension is not available
@@ -54,6 +54,13 @@ echo bcround('2.5', 0, \RoundingMode::HalfAwayFromZero);  // 3
 echo bcround('2.5', 0, \RoundingMode::HalfTowardsZero);   // 2
 echo bcround('2.5', 0, \RoundingMode::HalfEven);          // 2
 echo bcround('2.5', 0, \RoundingMode::HalfOdd);           // 3
+echo bcround('2.5', 0, \RoundingMode::TowardsZero);       // 2
+echo bcround('2.5', 0, \RoundingMode::AwayFromZero);      // 3
+echo bcround('2.5', 0, \RoundingMode::PositiveInfinity);  // 3
+echo bcround('2.5', 0, \RoundingMode::NegativeInfinity);  // 2
+
+// bcdivmod() returns [quotient, remainder]
+[$quot, $rem] = bcdivmod('17', '5');  // ['3', '2']
 ```
 
 ## 📋 Supported Functions
@@ -74,20 +81,39 @@ echo bcround('2.5', 0, \RoundingMode::HalfOdd);           // 3
 - `bcfloor()` - Round down to the nearest integer
 - `bcceil()` - Round up to the nearest integer
 - `bcround()` - Round to a specified precision with configurable rounding modes
+- `bcdivmod()` - Get the quotient and remainder of a division in a single call
 
 #### RoundingMode Enum Support
-The `bcround()` function supports PHP 8.4's `RoundingMode` enum through a polyfill for PHP 8.1-8.3:
+The `bcround()` function supports PHP 8.4's `RoundingMode` enum through a polyfill for PHP 8.1-8.3.
+All eight native modes are implemented with exact, arbitrary-precision string arithmetic (no float
+fallback), so results match the native `bcround()` even for very large or high-precision numbers:
 
-**Supported Modes:**
 - `RoundingMode::HalfAwayFromZero` (equivalent to `PHP_ROUND_HALF_UP`)
 - `RoundingMode::HalfTowardsZero` (equivalent to `PHP_ROUND_HALF_DOWN`)
 - `RoundingMode::HalfEven` (equivalent to `PHP_ROUND_HALF_EVEN`)
 - `RoundingMode::HalfOdd` (equivalent to `PHP_ROUND_HALF_ODD`)
+- `RoundingMode::TowardsZero`
+- `RoundingMode::AwayFromZero`
+- `RoundingMode::NegativeInfinity`
+- `RoundingMode::PositiveInfinity`
+
+The legacy integer `PHP_ROUND_*` constants are also accepted for the four half-modes.
+
+> **Note:** The polyfilled `RoundingMode` is a *pure* enum, matching native PHP 8.4 (it has no
+> backing value; `->value` / `from()` / `tryFrom()` are intentionally unavailable).
+
+#### Interoperability with `symfony/polyfill-php84`
+
+`symfony/polyfill-php84` also declares `bcceil()`, `bcfloor()`, `bcround()` and `bcdivmod()`, but only
+when the native bcmath extension is **already loaded** (its purpose is to backport the new PHP 8.4
+functions to older PHP that already has bcmath). This package instead provides the full bcmath API for
+environments **without** the extension.
 
-**Not Yet Supported:**
-- `RoundingMode::TowardsZero` - Throws `ValueError` (planned for future release)
-- `RoundingMode::AwayFromZero` - Throws `ValueError` (planned for future release)  
-- `RoundingMode::NegativeInfinity` - Throws `ValueError` (planned for future release)
+When both packages are installed on an environment that *does* have the bcmath extension and runs
+**PHP 8.2/8.3**, both declare `bcceil()`/`bcfloor()`/`bcround()`; whichever autoloads first wins (the
+`function_exists()` guards prevent a fatal redeclaration). This package's rounding is implemented with a
+native-compatible string algorithm, so the numeric results are identical regardless of which
+implementation is used. On environments without the extension only this package is active.
 
 ## ⚡ Performance