Dear FreeType team,
I am a grad student of University of Waterloo. We have a project about
TTF. We are trying to translate TTF bytecode to some kind of 3-addr-code, and
optimize the 3-addr-code, then convert it back to bytecode.
We tested our program on arial.ttf, and found that there is a CALL
instruction in some fpgm, which calls an uncertain fixed point value( bytecode
attached below ).
As you can see, the callee is the result of a series of arithmetic
operations, ( 4096 DIV MIN(MAX(0, 64 SUB F26Dot6), 192) ADD 44 ), where 192
not even divides 4096.
So, I wonder how do you deal with such a call instruction, do you just
throw an exception? There is very few documentation about ttf we can find, so
your advice will be very helpful. I expect to here from you soon.
best wishes
Zeming
PUSH[ ]
17
FDEF[ ] /* FunctionDefinition */
DUP[ ] /* DuplicateTopStack */
ROUND[01] /* Round */
PUSHB[ ] /* 1 value pushed */
64
SUB[ ] /* Subtract */
PUSHB[ ] /* 1 value pushed */
0
MAX[ ] /* Maximum */
DUP[ ] /* DuplicateTopStack */
PUSHB[ ] /* 2 values pushed */
44 192
ROLL[ ] /* RollTopThreeStack */
MIN[ ] /* Minimum */
PUSHW[ ] /* 1 value pushed */
4096 /* word */
DIV[ ] /* Divide */
ADD[ ] /* Add */
CALL[ ] /* CallFunction */
GPV[ ] /* GetPVector */
ABS[ ] /* Absolute */
SWAP[ ] /* SwapTopStack */
ABS[ ] /* Absolute */
SUB[ ] /* Subtract */
NOT[ ] /* LogicalNot */
IF[ ] /* If */
PUSHB[ ] /* 1 value pushed */
3
SUB[ ] /* Subtract */
EIF[ ] /* EndIf */
ENDF[ ] /* EndFunctionDefinition */
_______________________________________________
Freetype-devel mailing list
[email protected]
https://lists.nongnu.org/mailman/listinfo/freetype-devel
