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[cff] Add comment to clarify current implementation of `pop' operator.

This commit is contained in:
Werner Lemberg 2010-08-06 06:55:09 +02:00
parent 948076cd85
commit 223cb1b57c
1 changed files with 18 additions and 0 deletions
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18
src/cff/cffgload.c
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@ -2280,6 +2280,8 @@
/* subsequent `pop' operands should add the arguments, */
/* this is the implementation described for `unknown' other */
/* subroutines in the Type1 spec. */
/* */
/* XXX Fix return arguments (see discussion below). */
args -= 2 + ( args[-2] >> 16 );
if ( args < stack )
goto Stack_Underflow;
@ -2292,6 +2294,22 @@
FT_TRACE4(( " pop (invalid op)\n" ));
/* XXX Increasing `args' is wrong: After a certain number of */
/* `pop's we get a stack overflow. Reason for doing it is */
/* code like this (actually found in a CFF font): */
/* */
/* 17 1 3 callothersubr */
/* pop */
/* callsubr */
/* */
/* Since we handle `callothersubr' as a no-op, and */
/* `callsubr' needs at least one argument, `pop' can't be a */
/* no-op too as it basically should be. */
/* */
/* The right solution would be to provide real support for */
/* `callothersubr' as done in `t1decode.c', however, given */
/* the fact that CFF fonts with `pop' are invalid, it is */
/* questionable whether it is worth the time. */
args++;
break;