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Add third byte to the result in the adder

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CrazyEttin 2022-08-03 22:15:45 +03:00
parent 9474cb7864
commit 674ba2df08
1 changed files with 41 additions and 16 deletions
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57
examples/adder.asm
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@ -3,6 +3,8 @@
;Print a prompt ;Print a prompt
start: load r0, prompt start: load r0, prompt
store ffff, r0 store ffff, r0
load r0, space
store ffff, r0
;Read and convert the first argument and store it to arg1 ;Read and convert the first argument and store it to arg1
cleq r0, r0, rarg cleq r0, r0, rarg
@ -14,6 +16,8 @@ start: load r0, prompt
;Print a plus sign ;Print a plus sign
load r0, plus load r0, plus
store ffff, r0 store ffff, r0
load r0, space
store ffff, r0
;Read and convert the second argument and load it to r2 ;Read and convert the second argument and load it to r2
cleq r0, r0, rarg cleq r0, r0, rarg
@ -26,16 +30,21 @@ start: load r0, prompt
;Print a newline ;Print a newline
cleq r0, r0, newln cleq r0, r0, newln
;Print an equals sign
load r3, equals
store ffff, r3
;Add the arguments and load the result to r3 ;Add the arguments and load the result to r3
cleq r0, r0, adder cleq r0, r0, adder
xor r3, r3 xor r3, r3
xor r3, r0 xor r3, r0
;Print an equals sign
load r0, equals
store ffff, r0
;Convert and print the result ;Convert and print the result
;Overflow
xor r0, r0
xor r0, r1
cleq r0, r0, n2hex
store ffff, r0
;Restore the result back to r0 ;Restore the result back to r0
xor r0, r0 xor r0, r0
xor r0, r3 xor r0, r3
@ -90,10 +99,10 @@ rarg3: or r0, r2
ret ret
;Print a newline ;Print a newline
newln: load r1, cr newln: load r3, cr
store ffff, r1 store ffff, r3
load r1, lf load r3, lf
store ffff, r1 store ffff, r3
ret ret
;Get the value of a hexadecimal digit ;Get the value of a hexadecimal digit
@ -183,21 +192,32 @@ valf: load r0, tbl1e
;Return ;Return
h2nend: ret h2nend: ret
;Add r2 to r0 ;Add r2 to r0 with the overflow stored in r1
;Reset overflow
adder: xor r3, r3
store ovrflw, r3
;Copy the first argument to r1 ;Copy the first argument to r1
adder: xor r1, r1 addlop: xor r1, r1
xor r1, r0 xor r1, r0
;Calculate the sum and carry ;Calculate the sum and carry and copy the pre-shift carry to r1
xor r0, r2 xor r0, r2
and r2, r1 and r2, r1
xor r1, r1
xor r1, r2
shl r2 shl r2
;Check for overflow
rol r1
breq r1, r2, nvrflw
;Store overflow
load r1, one
store ovrflw, r1
;Check for no carry ;Check for no carry
xor r3, r3 nvrflw: breq r2, r3, addend
breq r2, r3, addend
;Loop ;Loop
breq r0, r0, adder breq r0, r0, addlop
;Return ;Load overflow and return
addend: ret addend: load r1, ovrflw
ret
;Get the hexadecimal digit of a nibble ;Get the hexadecimal digit of a nibble
;Extract the low nibble ;Extract the low nibble
@ -273,6 +293,7 @@ dgtf: load r0, tbl1f
n2hend: ret n2hend: ret
;Characters ;Characters
space: data 20
prompt: data 3e prompt: data 3e
plus: data 2b plus: data 2b
equals: data 3d equals: data 3d
@ -284,6 +305,9 @@ lf: data a
;Mask ;Mask
mask: data f mask: data f
;One
one: data 1
;Hexadecimal table ;Hexadecimal table
;Numeric digits ;Numeric digits
tbl00: data 0 tbl00: data 0
@ -334,4 +358,5 @@ tbl2a: data f
tbl2b: data 66 tbl2b: data 66
;First argument ;First argument
ovrflw: data 0
arg1: data 0 arg1: data 0