hex.ptr_index

dst[:w/4] = ptr + index*2w — the address of the index-th dw-aligned op past *ptr.

dst, ptr are hex[:w/4]; index is a signed hex[:w/4]. Works for negative index too.

@Assumes: w in {16, 32, 64, 128}.

Signature

def ptr_index dst, ptr, index { ... }

Defined in hex/pointers/pointer_arithmetics.fj — lines 45–51 (view on GitHub).

Complexity

• Time: w(2.25@+5.25)    // for w=64

• Space: w(2.25@+40)      // for w=64

See the complexity glossary for what @, w, dw, dbit, n mean.

Requires init

The following must be initialised before this macro is invoked:

• hex.add.init (or hex.init)

Source

Click to view the macro body

def ptr_index dst, ptr, index {
    .mov w/4, dst, index
    .shl_hex w/4, dst
    rep(8-#w, i) .shr_bit w/4, dst
    .shl_hex w/4, dst
    .add w/4, dst, ptr
}

Depends on

• hex.add/3

• hex.mov/3

• hex.shl_hex/2

Used by

• hex.read_nth_byte

• hex.read_nth_hex

• hex.write_nth_byte

• hex.write_nth_hex

Example uses

• hex.read_nth_hex in hex/pointers/read_pointers.fj

• hex.read_nth_byte in hex/pointers/read_pointers.fj

• hex.write_nth_hex in hex/pointers/write_pointers.fj

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