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; Copyright (c) 1998-2002,2004,2006-2016 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

; with unsigned numbers for convenience, although one supported

; ancillary chunk uses signed (two's complement) numbers.

align 4

proc png_save_uint_32 uses eax edi, buf:dword, i:dword

	mov eax,[i]

	bswap eax

	mov edi,[buf]

	stosd

	ret

endp

; The parameter is declared unsigned int, not uint_16,

; just to avoid potential problems on pre-ANSI C compilers.

align 4

proc png_save_uint_16 uses eax edi, buf:dword, i:dword

	mov eax,[i]

	ror eax,16

	bswap eax

	mov edi,[buf]

	stosw

	ret

endp

; the magic bytes of the signature, or more likely, the PNG stream is

; being embedded into another stream and doesn't need its own signature,

; we should call png_set_sig_bytes() to tell libpng how many of the

; bytes have already been written.

png_signature db 137, 80, 78, 71, 13, 10, 26, 10

align 4

proc png_write_sig uses eax ebx edi, png_ptr:dword

if PNG_IO_STATE_SUPPORTED eq 1

	; Inform the I/O callback that the signature is being written

	mov edi,[png_ptr]

	mov dword[edi+png_struct.io_state], PNG_IO_WRITING or PNG_IO_SIGNATURE

end if

	movzx eax,byte[edi+png_struct.sig_bytes]

	mov ebx,8

	sub ebx,eax

	add eax,png_signature

	stdcall png_write_data, edi, eax, ebx

	jge @f

		or dword[edi+png_struct.mode], PNG_HAVE_PNG_SIGNATURE

	@@:

	ret

endp

; The total_length is the sum of the lengths of all the data you will be

; passing in png_write_chunk_data().

align 4

proc png_write_chunk_header uses ebx edi, png_ptr:dword, chunk_name:dword, length:dword

locals

	buf rb 8 ;ebp-8

endl

;   PNG_CSTRING_FROM_CHUNK(buf, chunk_name);

;   png_debug2(0, "Writing %s chunk, length = %lu", buf, (unsigned long)length);

;end if

	cmp edi,0

	je .end_f ;if (png_ptr == NULL) return

	; Inform the I/O callback that the chunk header is being written.

	; PNG_IO_CHUNK_HDR requires a single I/O call.

end if

	mov ebx,ebp

	sub ebx,8

	stdcall png_save_uint_32, ebx, [length]

	m2m dword[ebx+4],dword[chunk_name]

	stdcall png_write_data, edi, ebx, 8

	m2m dword[edi+png_struct.chunk_name],dword[chunk_name]

	stdcall png_reset_crc, edi

	sub ebx,4 ;buf + 4

	stdcall png_calculate_crc, edi, ebx, 4

	; Inform the I/O callback that chunk data will (possibly) be written.

	; PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls.

end if

.end_f:

	ret

endp

align 4

proc png_write_chunk_start uses eax, png_ptr:dword, chunk_string:dword, length:dword

	mov eax,[chunk_string]

	stdcall png_write_chunk_header, [png_ptr], [eax], [length]

	ret

endp

; Note that multiple calls to this function are allowed, and that the

; sum of the lengths from these calls *must* add up to the total_length

; given to png_write_chunk_header().

align 4

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

	; Write the data, and run the CRC over it

	mov edi,[png_ptr]

	cmp edi,0

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

	je .end_f

	cmp dword[length],0

	jle .end_f ;if (..!=0 && ..>0)

		stdcall png_write_data, edi, [p2data], [length]

		; Update the CRC after writing the data,

		; in case the user I/O routine alters it.

		stdcall png_calculate_crc, edi, [p2data], [length]

.end_f:

	ret

endp

;void (png_structrp png_ptr)

align 4

proc png_write_chunk_end uses ebx edi, png_ptr:dword

locals

	buf rb 4 ;ebp-4

endl

	mov edi,[png_ptr]

	cmp edi,0

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

	; Inform the I/O callback that the chunk CRC is being written.

	; PNG_IO_CHUNK_CRC requires a single I/O function call.

end if

	mov ebx,ebp

	sub ebx,4

	stdcall png_save_uint_32, ebx, [edi+png_struct.crc]

.end_f:

	ret

endp

; representing the chunk name.  The array must be at least 4 bytes in

; length, and does not need to be null terminated.  To be safe, pass the

; pre-defined chunk names here, and if you need a new one, define it

; where the others are defined.  The length is the length of the data.

; All the data must be present.  If that is not possible, use the

; png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()

; functions instead.

align 4

proc png_write_complete_chunk uses edi, png_ptr:dword, chunk_name:dword, p3data:dword, length:dword

	mov edi,[png_ptr]

	cmp edi,0

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

	cmp dword[length],PNG_UINT_31_MAX ;if(..>..)

	jle @f

		png_error edi, 'length exceeds PNG maximum'

	@@:

	stdcall png_write_chunk_header, edi, [chunk_name], [length]

	stdcall png_write_chunk_data, edi, [p3data], [length]

	stdcall png_write_chunk_end, edi

.end_f:

	ret

endp

;void (png_structrp png_ptr, bytep chunk_string, bytep data, png_size_t length)

align 4

proc png_write_chunk, png_ptr:dword, chunk_string:dword, p3data:dword, length:dword

	stdcall png_write_complete_chunk, [png_ptr], [chunk_string], [p3data], [length]

	ret

endp

; so it only needs to be accurate if the size is less than 16384 bytes (the

; point at which a lower LZ window size can be used.)

align 4

proc png_image_size uses ebx ecx edx edi esi, png_ptr:dword

; Only return sizes up to the maximum of a uint_32; do this by limiting

; the width and height used to 15 bits.

	mov ebx,[edi+png_struct.height]

	jge .end0

	cmp ebx,32768

	jge .end0 ;if (..<..  && ..<..)

		cmp byte[edi+png_struct.interlaced],0

		je .end1 ;if (..!=0)

			; Interlacing makes the image larger because of the replication of

			; both the filter byte and the padding to a byte boundary.

			xor ecx,ecx

			.cycle0:

				PNG_PASS_COLS [edi+png_struct.width], ecx

				;eax = pw

				jle @f ;if (..>0)

					mov edx,eax

					movzx eax,byte[edi+png_struct.pixel_depth]

					PNG_ROWBYTES eax, edx

					inc eax

					mov edx,eax

					PNG_PASS_ROWS ebx, ecx

					imul eax,edx

					add esi,eax

				@@:

				inc ecx

				cmp ecx,6

				jle .cycle0

			jmp .end_f

		.end1: ;else

			mov eax,[edi+png_struct.rowbytes]

			inc eax

			imul eax,ebx

			jmp .end_f

	.end0: ;else