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; Copyright (c) 1998-2002,2004,2006-2014,2016 Glenn Randers-Pehrson

; (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)

; (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

; For conditions of distribution and use, see the disclaimer

; and license in png.inc

; special handling are expected to write functions that have the same

; arguments as these and perform similar functions, but that possibly

; use different output methods.  Note that you shouldn't change these

; functions, but rather write replacement functions and then change

; them at run time with png_set_write_fn(...).

; writes to a file pointer.  Note that this routine sometimes gets called

; with very small lengths, so you should implement some kind of simple

; buffering if you are using unbuffered writes.  This should never be asked

; to write more than 64K on a 16-bit machine.

align 4

proc png_write_data uses edi, png_ptr:dword, p2data:dword, length:dword

	; NOTE: write_data_fn must not change the buffer!

	mov edi,[png_ptr]

	cmp dword[edi+png_struct.write_data_fn],0

	je @f ;if (..!=0)

		stdcall dword[edi+png_struct.write_data_fn], edi, [p2data], [length]

		jmp .end_f

	@@: ;else

		png_error edi, 'Call to NULL write function'

	.end_f:

	ret

endp

; not writing to a standard C stream, you should create a replacement

; write_data function and use it at run time with png_set_write_fn(), rather

; than changing the library.

align 4

proc png_default_write_data uses eax edi, png_ptr:dword, p2data:dword, length:dword

;   png_size_t check;

	cmp edi,0

	je .end_f ;if (..==0) return

;      png_error(png_ptr, "Write Error");

.end_f:

	ret

endp

; to disk).  After png_flush is called, there should be no data pending

; writing in any buffers.

align 4

proc png_flush uses edi, png_ptr:dword

	mov edi,[png_ptr]

	cmp dword[edi+png_struct.output_flush_fn],0

	je @f ;if (..!=..)

		stdcall dword[edi+png_struct.output_flush_fn],edi

	@@:

	ret

endp

align 4

proc png_default_flush uses eax edi, png_ptr:dword

	mov edi,[png_ptr]

	cmp edi,0

	je @f ;if (..==0) return

;;;		stdcall fflush, [edi+png_struct.io_ptr]

	@@:

	ret

endp

; libpng if standard C streams aren't being used.

; png_ptr       - pointer to a png output data structure

; io_ptr        - pointer to user supplied structure containing info about

;                 the output functions.  May be NULL.

; write_data_fn - pointer to a new output function that takes as its

;                 arguments a pointer to a png_struct, a pointer to

;                 data to be written, and a 32-bit unsigned int that is

;                 the number of bytes to be written.  The new write

;                 function should call png_error(png_ptr, "Error msg")

;                 to exit and output any fatal error messages.  May be

;                 NULL, in which case libpng's default function will

;                 be used.

; flush_data_fn - pointer to a new flush function that takes as its

;                 arguments a pointer to a png_struct.  After a call to

;                 the flush function, there should be no data in any buffers

;                 or pending transmission.  If the output method doesn't do

;                 any buffering of output, a function prototype must still be

;                 supplied although it doesn't have to do anything.  If

;                 PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile

;                 time, output_flush_fn will be ignored, although it must be

;                 supplied for compatibility.  May be NULL, in which case

;                 libpng's default function will be used, if

;                 PNG_WRITE_FLUSH_SUPPORTED is defined.  This is not

;                 a good idea if io_ptr does not point to a standard

;                 *FILE structure.

;    png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)

align 4

proc png_set_write_fn uses eax edi, png_ptr:dword, io_ptr:dword, write_data_fn:dword, output_flush_fn:dword

	mov edi,[png_ptr]

	cmp edi,0

	je .end_f ;if (..==0) return

	mov [edi+png_struct.io_ptr],eax

	mov eax,png_default_write_data ;else

	cmp dword[write_data_fn],0

	je @f ;if (..!=0)

		mov eax,[write_data_fn]

	@@:

else

	mov eax,[write_data_fn]

end if

	mov [edi+png_struct.write_data_fn],eax

	if PNG_STDIO_SUPPORTED eq 1

		mov eax,[png_default_flush] ;else

		cmp dword[output_flush_fn],0

		je @f ;if (..!=0)

			mov eax,[output_flush_fn]

		@@:

	else

		mov eax,[output_flush_fn]

	end if

	mov [edi+png_struct.output_flush_fn],eax

end if ;WRITE_FLUSH

	; It is an error to read while writing a png file

	cmp dword[edi+png_struct.read_data_fn],0

	je @f ;if (..!=0)

		mov dword[edi+png_struct.read_data_fn], 0

	@@:

end if

.end_f:

	ret

endp