## heap-tags.pkg
# Compiled by:
# src/lib/compiler/core.sublib# The encoding of heap-chunk description headers.
#
# This is a Mythryl-level version of
#
# src/c/h/heap-tags.h
#
# WARNING: The following definitions must
# stay in sync with those in:
#
# src/c/h/heap-tags.h
# src/lib/std/src/unsafe/unsafe-chunk.pkg# src/lib/core/init/core.pkgstipulate
package un = unt; # unt is from src/lib/std/unt.pkg package lu = large_unt; # large_unt is from src/lib/std/large-unt.pkgherein
package heap_tags
: Heap_Tags # Heap_Tags is from src/lib/compiler/back/low/main/main/heap-tags.api {
Btag = Unt; # Exported as opaque type to client packages.
tag_width = 7; # 5 minor tag bits plus 2 major tag bits
#
# WARNING: Above must track the
# src/c/h/heap-tags.h
# definition of
# TAGWORD_LENGTH_FIELD_SHIFT
# 'max_length' is max value storable in
# a tagword 'length' field, plus one.
# (Sign should be 0.)
#
max_length = un::to_int (un::(<<) (0u1, un::(-) (0u31, un::from_int tag_width))); # 64-BIT-ISSUE
pow_tag_width = un::to_int (un::(<<) (0u1, un::from_int tag_width)); # 1 << tag_width == 2**tag_width == 1 << 7 == 0b10000000 == 0x80.
# Btag values:
#
stipulate
fun make_btag t = un::bitwise_or (un::(<<) (t, 0u2), 0u2);
herein
# Note that our btags here are pre-shifted (and a-tagged)
# relative to those in src/c/h/heap-tags.h
#
pairs_and_records_btag = make_btag 0u0;
ro_vector_header_btag = make_btag 0u1;
rw_vector_header_btag = make_btag 0u2;
rw_vector_data_btag = make_btag 0u3;
four_byte_aligned_nonpointer_data_btag = make_btag 0u4;
eight_byte_aligned_nonpointer_data_btag = make_btag 0u5;
weak_pointer_or_suspension_btag = make_btag 0u6;
#
ro_vector_data_btag = pairs_and_records_btag; # The cleaner does not need to distinguish read-only vector data records from other records.
refcell_btag = rw_vector_data_btag; # To the cleaner, a refcell is just a one-element vector.
end;
#
# WARNING: The above must track the
# src/c/h/heap-tags.h
# definitions
# #define PAIRS_AND_RECORDS_BTAG HEXLIT( 0 ) # Records (including pairs).
# #define RO_VECTOR_HEADER_BTAG HEXLIT( 1 ) # ro_vector header: length is C-tag.
# #define RW_VECTOR_HEADER_BTAG HEXLIT( 2 ) # rw_vector header: length is C-tag.
# #define RW_VECTOR_DATA_BTAG HEXLIT( 3 ) # typeagnostic rw_vector data.
# #define FOUR_BYTE_ALIGNED_NONPOINTER_DATA_BTAG HEXLIT( 4 ) # 32-bit aligned non-pointer data.
# #define EIGHT_BYTE_ALIGNED_NONPOINTER_DATA_BTAG HEXLIT( 5 ) # 64-bit aligned non-pointer data.
# #define WEAK_POINTER_OR_SUSPENSION_BTAG HEXLIT( 6 ) # "Special chunk" (weak pointer or suspension): C-tag is stored in 'length' field.
# Build a tagword from a B-tag and a length: # The A-tag on a tagword is always 2.
#
fun make_tagword (len, btag)
=
lu::bitwise_or (lu::(<<) (lu::from_int len, un::from_int tag_width), un::to_large_unt btag);
# Codes for rw_vector/vector headers.
#
typeagnostic_vector_ctag = 0;
vector_of_one_byte_unts_ctag = 1;
unt16_vector_ctag = 2;
tagged_int_vector_ctag = 3;
int1_vector_ctag = 4;
vector_of_four_byte_floats_ctag = 5;
vector_of_eight_byte_floats_ctag = 6;
#
# WARNING: The above must track the
# src/c/h/heap-tags.h
# definitions
# #define TYPEAGNOSTIC_VECTOR_CTAG HEXLIT( 0 )
# #define VECTOR_OF_ONE_BYTE_UNTS_CTAG HEXLIT( 1 )
# #define UNT16_VECTOR_CTAG HEXLIT( 2 )
# #define TAGGED_INT_VECTOR_CTAG HEXLIT( 3 )
# #define INT1_VECTOR_CTAG HEXLIT( 4 ) // Never used.
# #define VECTOR_OF_FOUR_BYTE_FLOATS_CTAG HEXLIT( 5 )
# #define VECTOR_OF_EIGHT_BYTE_FLOATS_CTAG HEXLIT( 6 )
# Fixed descriptors: length / c-tag b-tag
# ----------------------- ------------------------------------------
pair_tagword = make_tagword ( 2, pairs_and_records_btag );
refcell_tagword = make_tagword ( 1, refcell_btag );
float64_tagword = make_tagword ( 2, eight_byte_aligned_nonpointer_data_btag );
typeagnostic_ro_vector_tagword = make_tagword (typeagnostic_vector_ctag, ro_vector_header_btag );
typeagnostic_rw_vector_tagword = make_tagword (typeagnostic_vector_ctag, rw_vector_header_btag );
weak_pointer_or_suspension_tagword = make_tagword ( 0, weak_pointer_or_suspension_btag );
# "Special" (everything-else) descriptors.
#
unevaluated_lazy_suspension_ctag = 0;
evaluated_lazy_suspension_ctag = 1;
weak_pointer_ctag = 2;
nulled_weak_pointer_ctag = 3;
#
# The above must track the
# src/c/h/heap-tags.h
# definitions
# #define UNEVALUATED_LAZY_SUSPENSION_CTAG 0
# #define EVALUATED_LAZY_SUSPENSION_CTAG 1
# #define WEAK_POINTER_CTAG 2
# #define NULLED_WEAK_POINTER_CTAG 3
# and the
# src/lib/core/init/core.pkg # definitions
# unevaluated_lazy_suspension_ctag = 0;
# evaluated_lazy_suspension_ctag = 1;
# and the
# src/lib/std/src/nj/weak-reference.pkg # definition
# weak_pointer_ctag = 2;
};
end;
## COPYRIGHT (c) 1998 Bell Labs, Lucent Technologies.
## Subsequent changes by Jeff Prothero Copyright (c) 2010-2015,
## released per terms of SMLNJ-COPYRIGHT.