macro fltDat {}

fltDat "5.55" ;convert text to dd 5.55

flt1 equ '4.5430'
fltDat flt1 ;convert text to dd 4.5430
    

db 'dd ', fltDat, 13, 10, 'dd ', fil1    

fasm -m 1024 ./temp.asm ./temp.fasm
flat assembler  version 1.73.30  (1024 kilobytes memory)
1 passes, 15 bytes.    

fasm -m 1024 ./temp.fasm ./temp.bin
flat assembler  version 1.73.30  (1024 kilobytes memory)
1 passes, 8 bytes.    

; data section
file 'temp.bin'    

macro cvrt_int dir=dd, val&
{ ; It takes a long time to write in the browser. I'll write a little later. But the meaning is this:
  ; in the virtual block, you collect text using a separator character (say ';') and in the same virtual,
  ; you collect cycles of reading text by characters through repeat and accumulating values in a variable until you meet a separator.
  ; When you hit the separator, you save the accumulated value in, say, label and collect the label name in a list.
  ; After closing virtual, use dir to create values from this list by label names
}

; macro cvrt_flt ...    

include 'temp.fasm'    

Forth

Write a separate program to convert the text read from the file and save it to a binary file.

Third step not needed.

Fourth step (now the new third step):

Virtual at 0
Tabflts::
Txt   db "5.55"
      dd 5.55
      db "4.5430"
      dd 4.5430
end virtual

;or this
Virtual at 0
Tabflts::
Txt   db "5.55"
      db "4.5430"
end virtual
Virtual at 0
Flts::
      dd 5.55
      dd 4.5430
end virtual
    

macro fltDat str* {
  local buffer, next
  define buffer f
  rept 8 i:1 \{
        rept 1 c: str shr ((8-i)*8) and 0FFh - 48 \\{
          match f, buffer \\\{
             define next 0
             match -=48, c \\\\{ define next 1 \\\\}
             match -=2, c \\\\{ define buffer .\\\#f
                                define next 1 \\\\}
             match =0, next \\\\{ define buffer c\\\#f \\\\}
          \\\} \\} \}
  dd buffer
}

fltDat "5.55"

flt1 equ '4.5430'
fltDat flt1    

Well, if you are that desperate, you could try something like this:

macro fltDat str* {
  local buffer, next
  define buffer f
  rept 8 i:1 \{
        rept 1 c: str shr ((8-i)*8) and 0FFh - 48 \\{
          match f, buffer \\\{
             define next 0
             match -=48, c \\\\{ define next 1 \\\\}
             match -=2, c \\\\{ define buffer .\\\#f
                                define next 1 \\\\}
             match =0, next \\\\{ define buffer c\\\#f \\\\}
          \\\} \\} \}
  dd buffer
}

fltDat "5.50000500000"

flt1 equ '4.54300000000000001'
fltDat flt1    

fasm -m 1024 ./temp.asm ./temp.fasm
flat assembler  version 1.73.30  (1024 kilobytes memory)
./temp.asm [16]:
fltDat "5.50000500000"
./temp.asm [5] fltDat [4]:
        rept 1 c: str shr ((8-i)*8) and 0FFh - 48 \\{
./temp.asm [5] rept [1]:
        rept 1 c: str shr ((8-i)*8) and 0FFh - 48 \\{
error: value out of range.    

fltDat "3.141592635389793238e-245" ; 25 characters! It won't fit into triple precision.    

For me normal 3.1415926 accuracy 7 digits

"-1.0" wrong value macro fltDat

             match -=3, c \\\\{ define buffer -f
                                define next 1 \\\\}    

1e6    

1E6    

1.2f    

1.61F    

3.2*1.8-2.1/7.8**-0.1+sqrt(7.02)