Replace lossy 2-bit truncation with rotation-based encoding for
64-bit word boxing with float64. The new scheme uses
rotl64(float_bits - ADDEND, 3) to embed floats inline with full
52-bit mantissa precision. Floats with exponents outside [-255,+256]
(0.0, NaN, Inf, very small/large values) fall back to heap-allocated
RFloat.
Co-authored-by: Claude <noreply@anthropic.com>
This commit adds Doxygen-style comments to several MRB_API functions
in the `src/etc.c` file. These comments explain the purpose,
parameters, and return values of these functions, improving code
readability and maintainability.
The following functions were commented:
- mrb_data_object_alloc
- mrb_data_check_type
- mrb_data_check_get_ptr
- mrb_data_get_ptr
- mrb_obj_to_sym
- mrb_obj_id
- mrb_word_boxing_float_value
- mrb_word_boxing_value_float
- mrb_word_boxing_cptr_value
- mrb_boxing_int_value
Embedding reduce memory consumption, sacrificing precision. It clips least
significant 2 bits from `mrb_float`, so if you need to keep float precision,
define `MRB_USE_FLOAT_FULL_PRECISION`.
`MRB_WORD_BOXING` and `MRB_INT64`:
`mrb_float` (`double`) is embedded in `mrb_value` clipped last 2 bits.
`MRB_WORD_BOXING` and `MRB_INT64` and `MRB_USE_FLOAT_FULL_PRECISION`:
`mrb_float` is allocated in the heaps wrapped by `struct RFloat`.
`MRB_WORD_BOXING` and `MRB_INT32` and `MRB_USE_FLOAT32`:
`mrb_float` (`float`) is embedded in `mrb_value` clipped last 2 bits.
In addition, to reserve bit space in the `mrb_value`, maximum inline
symbol length become 4 (instead of 5) in the configuration.
`MRB_WORD_BOXING` and `MRB_INT32`:
Assume `MRB_USE_FLOAT_FULL_PRECISION` and allocate Float values in heap.
- Integrate `Fixnum` and `Integer`
- Remove `Integral`
- `int / int -> int`
- Replace `mrb_fixnum()` to `mrb_int()`
- Replace `mrb_fixnum_value()` to `mrb_int_value()`.
- Use `mrb_integer_p()` instead of `mrb_fixnum_p()`
- `MRB_WITHOUT_FLOAT` => `MRB_NO_FLOAT`
- `MRB_USE_FLOAT` => `MRB_USE_FLOAT32`
The former is to use `USE_XXX` naming convention. The latter is to make
sure `float` is 32bit float and not floating point number in general.
Changes:
- `pool format is completely replaced
- supported types: `STR`, `INT32`, `INT64`, `FLOAT`
- `FLOAT` may be replaced by binary representation in the future
- insert `NUL` after string literals in `mrb` files
- `irep->pool` no longer store values in `mrb_value`
- instead it stores in `mrb_pool_value`
- less allocation
- `mrb_irep` can be stored in ROM
Previously, if `MRB_NAN_BOXING` is defined, for example,
`mrb_cptr_value()` could not keep an odd address.
If it is `MRB_32BIT`, it can be embedded in `NaN` as it is.
If it is `MRB_64BIT`, some operations are shared with `MRB_WORD_BOXING`.
In this case, the MRB_API function `mrb_nan_boxing_cptr_value()` is
defined.
The binary sizes (gems are only `mruby-bin-mruby`) are reduced slightly in
my environment than before the introduction of new specifiers/modifiers
(5116789a) with this change.
------------+-------------------+-------------------+--------
BINARY | BEFORE (5116789a) | AFTER (This PR) | RATIO
------------+-------------------+-------------------+--------
mruby | 593416 bytes | 593208 bytes | -0.04%
libmruby.a | 769048 bytes | 767264 bytes | -0.23%
------------+-------------------+-------------------+--------
BTW, I accidentally changed `tasks/toolchains/visualcpp.rake` at #4613,
so I put it back.
Before this patch:
$ bin/mruby -e '1.respond_to?(2)' #=> nil is not a symbol
After this patch (same as Ruby):
$ bin/mruby -e '1.respond_to?(2)' #=> 2 is not a symbol nor a string
We assume meta-programming is less used in embedded environments.
We have moved following methods:
* Kernel module
global_variables, local_variables, singleton_class,
instance_variables, instance_variables_defined?, instance_variable_get,
instance_variable_set, methods, private_methods, public_methods,
protected_methods, singleton_methods, define_singleton_methods
* Module class
class_variables, class_variables_defined?, class_variable_get,
class_variable_set, remove_class_variable, included_modules,
instance_methods, remove_method, method_removed, constants
* Module class methods
constants, nesting
Note:
Following meta-programming methods are kept in the core:
* Module class
alias_method, undef_method, ancestors, const_defined?, const_get,
const_set, remove_const, method_defined?, define_method
* Toplevel object
define_method
`mruby-metaprog` gem is linked by default (specified in default.gembox).
When it is removed, it will save 40KB (stripped:8KB) on x86-64
environment last time I measured.
Inline structures have no instance variables, no finalizer, and offer as much space as possible in RBASIC object. This means 24 bytes on 64-bit platforms and 12 bytes on 32-bit platforms.
mruby-inline-struct gem is only provided for testing.
_snprintf is not C99's snprintf!
This simple implementation, unlike _snprintf,
always null-terminates and returns the expected
return value (in most cases).
Other C99 behaviors (like format specifiers) require
adding a complete snprintf implementation.
Do we want or need that?
The same applies to vsnprintf (aka _vsnprintf).
Yukihiro "Matz" Matsumoto