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-rw-r--r--src/cff/cf2stack.c90
1 files changed, 85 insertions, 5 deletions
diff --git a/src/cff/cf2stack.c b/src/cff/cf2stack.c
index 8332b5d..8f3adb6 100644
--- a/src/cff/cf2stack.c
+++ b/src/cff/cf2stack.c
@@ -53,14 +53,14 @@
cf2_stack_init( FT_Memory memory,
FT_Error* e )
{
- FT_Error error = FT_Err_Ok; /* for FT_QNEW */
+ FT_Error error = FT_Err_Ok; /* for FT_NEW */
CF2_Stack stack = NULL;
- if ( !FT_QNEW( stack ) )
+ if ( !FT_NEW( stack ) )
{
- /* initialize the structure; FT_QNEW zeroes it */
+ /* initialize the structure; FT_NEW zeroes it */
stack->memory = memory;
stack->error = e;
stack->top = &stack->buffer[0]; /* empty stack */
@@ -145,7 +145,7 @@
/* Note: type mismatch is silently cast */
- /* TODO: check this */
+ /* TODO: check this */
FT_LOCAL_DEF( CF2_Fixed )
cf2_stack_popFixed( CF2_Stack stack )
{
@@ -170,7 +170,7 @@
/* Note: type mismatch is silently cast */
- /* TODO: check this */
+ /* TODO: check this */
FT_LOCAL_DEF( CF2_Fixed )
cf2_stack_getReal( CF2_Stack stack,
CF2_UInt idx )
@@ -195,6 +195,86 @@
}
+ FT_LOCAL( void )
+ cf2_stack_roll( CF2_Stack stack,
+ CF2_Int count,
+ CF2_Int shift )
+ {
+ /* we initialize this variable to avoid compiler warnings */
+ CF2_StackNumber last = { { 0 }, CF2_NumberInt };
+
+ CF2_Int start_idx, idx, i;
+
+
+ if ( count < 2 )
+ return; /* nothing to do (values 0 and 1), or undefined value */
+
+ if ( (CF2_UInt)count > cf2_stack_count( stack ) )
+ {
+ CF2_SET_ERROR( stack->error, Stack_Overflow );
+ return;
+ }
+
+ if ( shift < 0 )
+ shift = -( ( -shift ) % count );
+ else
+ shift %= count;
+
+ if ( shift == 0 )
+ return; /* nothing to do */
+
+ /* We use the following algorithm to do the rolling, */
+ /* which needs two temporary variables only. */
+ /* */
+ /* Example: */
+ /* */
+ /* count = 8 */
+ /* shift = 2 */
+ /* */
+ /* stack indices before roll: 7 6 5 4 3 2 1 0 */
+ /* stack indices after roll: 1 0 7 6 5 4 3 2 */
+ /* */
+ /* The value of index 0 gets moved to index 2, while */
+ /* the old value of index 2 gets moved to index 4, */
+ /* and so on. We thus have the following copying */
+ /* chains for shift value 2. */
+ /* */
+ /* 0 -> 2 -> 4 -> 6 -> 0 */
+ /* 1 -> 3 -> 5 -> 7 -> 1 */
+ /* */
+ /* If `count' and `shift' are incommensurable, we */
+ /* have a single chain only. Otherwise, increase */
+ /* the start index by 1 after the first chain, then */
+ /* do the next chain until all elements in all */
+ /* chains are handled. */
+
+ start_idx = -1;
+ idx = -1;
+ for ( i = 0; i < count; i++ )
+ {
+ CF2_StackNumber tmp;
+
+
+ if ( start_idx == idx )
+ {
+ start_idx++;
+ idx = start_idx;
+ last = stack->buffer[idx];
+ }
+
+ idx += shift;
+ if ( idx >= count )
+ idx -= count;
+ else if ( idx < 0 )
+ idx += count;
+
+ tmp = stack->buffer[idx];
+ stack->buffer[idx] = last;
+ last = tmp;
+ }
+ }
+
+
FT_LOCAL_DEF( void )
cf2_stack_clear( CF2_Stack stack )
{