Added the function FT_Read_Fields, it acts as a
finite-state automata to load large TrueType tables in object structures. This is experimental, don't mess too much with it, thanks :-)
This commit is contained in:
David Turner
parent
1d1c7eb807
commit
818336fdf4
@ -429,3 +429,149 @@
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return 0;
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}
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BASE_FUNC
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FT_Error FT_Read_Fields( FT_Stream stream,
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const FT_Frame_Field* fields,
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void* structure )
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{
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FT_Error error;
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FT_Bool frame_accessed = 0;
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if (!fields || !stream)
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return FT_Err_Invalid_Argument;
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error = FT_Err_Ok;
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do
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{
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FT_ULong value;
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FT_Int sign_shift;
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FT_Byte* p;
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switch (fields->value)
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{
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case ft_frame_start: /* access a new frame */
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{
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error = FT_Access_Frame( stream, fields->offset );
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if (error) goto Exit;
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frame_accessed = 1;
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fields++;
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continue; /* loop ! */
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}
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case ft_frame_byte:
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case ft_frame_schar: /* read a single byte */
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{
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value = GET_Byte();
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sign_shift = 24;
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break;
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}
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case ft_frame_short_be:
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case ft_frame_ushort_be: /* read a 2-byte big-endian short */
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{
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value = GET_UShort();
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sign_shift = 16;
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break;
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}
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case ft_frame_short_le:
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case ft_frame_ushort_le: /* read a 2-byte little-endian short */
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{
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char* p;
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value = 0;
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p = stream->cursor;
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if (p+1 < stream->limit)
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{
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value = (FT_UShort)p[0] | ((FT_UShort)p[1] << 8);
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stream->cursor += 2;
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}
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sign_shift = 16;
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break;
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}
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case ft_frame_long_be:
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case ft_frame_ulong_be: /* read a 4-byte big-endian long */
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{
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value = GET_ULong();
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sign_shift = 0;
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break;
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}
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case ft_frame_long_le:
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case ft_frame_ulong_le: /* read a 4-byte little-endian long */
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{
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char* p;
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value = 0;
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p = stream->cursor;
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if (p+3 < stream->limit)
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{
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value = (FT_ULong)p[0] |
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((FT_ULong)p[1] << 8) |
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((FT_ULong)p[2] << 16) |
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((FT_ULong)p[3] << 24);
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stream->cursor += 4;
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}
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sign_shift = 0;
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break;
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}
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case ft_frame_off3_be:
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case ft_frame_uoff3_be: /* read a 3-byte big-endian long */
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{
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value = GET_UOffset();
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sign_shift = 8;
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break;
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}
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case ft_frame_off3_le:
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case ft_frame_uoff3_le: /* read a 3-byte little-endian long */
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{
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char* p;
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value = 0;
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p = stream->cursor;
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if (p+3 < stream->limit)
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{
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value = (FT_ULong)p[0] |
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((FT_ULong)p[1] << 8) |
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((FT_ULong)p[2] << 16) |
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((FT_ULong)p[3] << 24);
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stream->cursor += 4;
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}
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sign_shift = 8;
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break;
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}
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default:
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/* otherwise, exit the loop */
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goto Exit;
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}
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/* now, compute the signed value is necessary */
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if (fields->value & FT_FRAME_OP_SIGNED)
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value = (FT_ULong)((FT_Long)(value << sign_shift) >> sign_shift);
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/* finally, store the value in the object */
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p = (FT_Byte*)structure + fields->offset;
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switch (fields->size)
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{
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case 1: *(FT_Byte*)p = (FT_Byte) value; break;
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case 2: *(FT_UShort*)p = (FT_UShort)value; break;
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case 4: *(FT_ULong*)p = (FT_ULong) value; break;
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default: ; /* ignore !! */
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}
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/* go to next field */
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fields++;
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}
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while (1);
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Exit:
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/* close the frame if it was opened by this read */
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if (frame_accessed)
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FT_Forget_Frame(stream);
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return error;
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}
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@ -3,6 +3,77 @@
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#include <ftobjs.h>
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/* format of an 8-bit frame_op value = [ xxxxx | e | s ] */
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/* where s is set to 1 when the value is signed.. */
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/* where e is set to 1 when the value is little-endian */
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/* xxxxx is a command */
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#define FT_FRAME_OP_SHIFT 2
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#define FT_FRAME_OP_SIGNED 1
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#define FT_FRAME_OP_LITTLE 2
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#define FT_FRAME_OP_COMMAND(x) (x >> FT_FRAME_OP_SHIFT)
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#define FT_MAKE_FRAME_OP( command, little, sign ) \
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((command << FT_FRAME_OP_SHIFT) | (little << 1) | sign)
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#define FT_FRAME_OP_END 0
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#define FT_FRAME_OP_START 1 /* start a new frame */
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#define FT_FRAME_OP_BYTE 2 /* read 1-byte value */
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#define FT_FRAME_OP_SHORT 3 /* read 2-byte value */
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#define FT_FRAME_OP_LONG 4 /* read 4-byte value */
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#define FT_FRAME_OP_OFF3 5 /* read 3-byte value */
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typedef enum FT_Frame_Op_
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{
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ft_frame_end = 0,
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ft_frame_start = FT_MAKE_FRAME_OP( FT_FRAME_OP_START, 0, 0 ),
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ft_frame_byte = FT_MAKE_FRAME_OP( FT_FRAME_OP_BYTE, 0, 0 ),
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ft_frame_schar = FT_MAKE_FRAME_OP( FT_FRAME_OP_BYTE, 0, 1 ),
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ft_frame_ushort_be = FT_MAKE_FRAME_OP( FT_FRAME_OP_SHORT, 0, 0 ),
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ft_frame_short_be = FT_MAKE_FRAME_OP( FT_FRAME_OP_SHORT, 0, 1 ),
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ft_frame_ushort_le = FT_MAKE_FRAME_OP( FT_FRAME_OP_SHORT, 1, 0 ),
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ft_frame_short_le = FT_MAKE_FRAME_OP( FT_FRAME_OP_SHORT, 1, 1 ),
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ft_frame_ulong_be = FT_MAKE_FRAME_OP( FT_FRAME_OP_LONG, 0, 0 ),
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ft_frame_ulong_le = FT_MAKE_FRAME_OP( FT_FRAME_OP_LONG, 0, 1 ),
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ft_frame_long_be = FT_MAKE_FRAME_OP( FT_FRAME_OP_LONG, 1, 0 ),
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ft_frame_long_le = FT_MAKE_FRAME_OP( FT_FRAME_OP_LONG, 1, 1 ),
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ft_frame_uoff3_be = FT_MAKE_FRAME_OP( FT_FRAME_OP_OFF3, 0, 0 ),
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ft_frame_uoff3_le = FT_MAKE_FRAME_OP( FT_FRAME_OP_OFF3, 0, 1 ),
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ft_frame_off3_be = FT_MAKE_FRAME_OP( FT_FRAME_OP_OFF3, 1, 0 ),
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ft_frame_off3_le = FT_MAKE_FRAME_OP( FT_FRAME_OP_OFF3, 1, 1 ),
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} FT_Frame_Op;
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typedef struct FT_Frame_Field_
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{
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FT_Frame_Op value;
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char size;
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FT_UShort offset;
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} FT_Frame_Field;
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/* make-up a FT_Frame_Field out of a structure type and a field name */
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#define FT_FIELD_REF(s,f) (((s*)0)->f)
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#define FT_FRAME_FIELD( frame_op, struct_type, field ) \
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{ \
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frame_op, \
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sizeof(FT_FIELD_REF(struct_type,field)), \
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(FT_UShort)(char*)&FT_FIELD_REF(struct_type,field) }
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#define FT_MAKE_EMPTY_FIELD( frame_op ) { frame_op, 0, 0 }
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#define FT_FRAME_LONG(s,f) FT_FRAME_FIELD( ft_frame_long_be, s, f )
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#define FT_FRAME_ULONG(s,f) FT_FRAME_FIELD( ft_frame_ulong_be, s, f )
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#define FT_FRAME_SHORT(s,f) FT_FRAME_FIELD( ft_frame_short_be, s, f )
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#define FT_FRAME_USHORT(s,f) FT_FRAME_FIELD( ft_frame_ushort_be, s, f )
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#define FT_FRAME_BYTE(s,f) FT_FRAME_FIELD( ft_frame_byte, s, f )
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#define FT_FRAME_CHAR(s,f) FT_FRAME_FIELD( ft_frame_schar, s, f )
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/*************************************************************************/
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/* */
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@ -134,6 +205,11 @@
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FT_Long FT_Read_Long( FT_Stream stream,
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FT_Error* error );
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BASE_DEF
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FT_Error FT_Read_Fields( FT_Stream stream,
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const FT_Frame_Field* fields,
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void* structure );
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#define USE_Stream( resource, stream ) \
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FT_SET_ERROR( FT_Open_Stream( resource, stream ) )
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@ -173,6 +249,7 @@
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(FT_Char*)buffer, \
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count ) )
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#define READ_Fields( fields, object ) \
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((error = FT_Read_Fields( stream, fields, object )) != FT_Err_Ok)
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#endif /* FTIO_H */
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