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- ; vim:ft=fasm:
- ; taken from: https://github.com/tgrysztar/fasmg
- ; Universal implementation of ALIGN.
- ; Basic use:
- ; align 4
- ; Ensure specific offset relative to an aligned address:
- ; align 4 | 1
- ; Provide information for the alignment of relocatable symbols:
- ; align.assume rbp, 16
- ; element RELOCATABLE_BASE
- ; org RELOCATABLE_BASE
- ; align.assume RELOCATABLE_BASE, 10000h
- ; Pad with value:
- ; align 16, 90h
- ; Use a custom command to pad:
- ; align 16, db # dup ($ and 0FFh)
- define align? align
- align?.count = 0
- calminstruction align?.assume? address*, alignment*
- local index, symbol
- compute address, address
- compute alignment, alignment
- check address relativeto 0
- jyes absolute
- compute index, 0
- find:
- check index = align.count
- jyes update
- arrange symbol, align.=address#index
- check address relativeto symbol
- jyes update
- compute index, index + 1
- jump find
- update:
- arrange symbol, align.=address#index
- publish symbol, address
- arrange symbol, align.=alignment#index
- publish symbol, alignment
- compute align.count, align.count + 1
- exit
- absolute:
- check address mod alignment = 0
- jyes ok
- err 'false assumption about absolute address'
- ok:
- end calminstruction
- calminstruction align? alignment*, filler:rb #
- local index, address, offset
- compute offset, 0
- match alignment | offset, alignment
- compute alignment, alignment
- check alignment >= 0
- jyes alignment_ok
- err 'invalid alignment value'
- exit
- alignment_ok:
- compute address, $
- check address relativeto 0
- jyes align
- compute index, 0
- find:
- check index = align.count
- jyes fail
- arrange symbol, align.=address#index
- check address relativeto symbol
- jyes found
- compute index, index + 1
- jump find
- found:
- compute address, address - symbol
- arrange symbol, align.=alignment#index
- check symbol > 0 & symbol mod alignment = 0
- jyes align
- fail:
- err 'variable portion of the address is not aligned enough'
- exit
- align:
- compute alignment, (alignment-1) - (address-offset+alignment-1) mod alignment
- local prefix, suffix
- match prefix? # suffix?, filler
- jyes custom
- arrange alignment, =db alignment =dup (filler)
- assemble alignment
- exit
- custom:
- arrange alignment, prefix alignment suffix
- assemble alignment
- end calminstruction
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