prog8/compiler/res/prog8lib/cx16/bmx.p8
2023-11-29 21:57:17 +01:00

334 lines
12 KiB
Lua

; Routines to load and save "BMX" files (commander X16 bitmap format) Version 1.
; Only uncompressed images are supported for now.
; BMX Specification: https://cx16forum.com/forum/viewtopic.php?t=6945
; TODO: ability to save "stamps" , bitmaps that are only a region of the screen.
; TODO: ability to just load the palette from a BMX file
%import diskio
bmx {
ubyte[32] header
str FILEID = petscii:"bmx"
ubyte bitsperpixel ; consider using set_bpp() when setting this
ubyte vera_colordepth ; consider using set_vera_colordepth() when setting this
uword width
uword height
ubyte border
uword palette_entries ; 1-256
ubyte palette_start
ubyte compression
uword palette_buffer_ptr = 0 ; should you want to load or save the palette into main memory instead of directly into vram
uword error_message ; pointer to error message, or 0 if all ok
ubyte old_drivenumber
sub open(ubyte drivenumber, str filename) -> bool {
; Open a BMX bitmap file and reads the header information.
; Returns true if all is ok, false otherwise + error_message will be set.
error_message = 0
old_drivenumber = diskio.drivenumber
diskio.drivenumber = drivenumber
if diskio.f_open(filename) {
diskio.reset_read_channel()
if read_header() {
if parse_header() {
if palette_entries>0 {
if width<=640 {
return true
} else
error_message = "image too large"
} else
error_message = "invalid bmx file"
} else
error_message = "invalid bmx file"
} else
error_message = "invalid bmx file"
} else
error_message = diskio.status()
close()
return false
}
sub close() {
; if you want to close the file before actually loading palette or bitmap data.
diskio.f_close()
diskio.drivenumber = old_drivenumber
}
sub continue_load(ubyte vbank, uword vaddr) -> bool {
; Continues loading the palette and bitmap data from the opened BMX file.
; Parameters: the vram bank and address where the bitmap data should go.
; You can set palette_buffer_ptr if you want the palette buffered rather than directly into vram.
; Note: does not change vera screen mode or colordepth! You have to do that yourself!
; Returns true if all is ok, false otherwise + error_message will be set.
error_message = 0
diskio.reset_read_channel()
if width==320 or width==640 {
if compression==0 {
if read_palette() {
if not read_bitmap(vbank, vaddr)
error_message = "bitmap error"
} else
error_message = "palette error"
} else
error_message = "compression not supported"
} else
error_message = "width not 320 or 640" ; note: use continue_load_stamp() to read other sizes
close()
return error_message==0
}
sub continue_load_stamp(ubyte vbank, uword vaddr, uword screenwidth) -> bool {
; Continues loading the palette and bitmap "stamp" data from the opened BMX file.
; "Stamp" means: load an image that is smaller than the screen (so we need to pad around it)
; Parameters:the vram bank and address where the bitmap data should go,
; and the screen width that the stamp image is loaded into.
; You can set palette_buffer_ptr if you want the palette buffered rather than directly into vram.
; Note: does not change vera screen mode or colordepth! You have to do that yourself!
; Returns true if all is ok, false otherwise + error_message will be set.
error_message = 0
diskio.reset_read_channel()
if compression==0 {
if read_palette() {
if not read_bitmap_padded(vbank, vaddr, screenwidth)
error_message = "bitmap error"
} else
error_message = "palette error"
} else
error_message = "compression not supported"
close()
return error_message==0
}
sub save(ubyte drivenumber, str filename, ubyte vbank, uword vaddr) -> bool {
; Save bitmap and palette data from vram into a BMX file.
; First you must have set all bmx.* variables to the correct values! (like width, height..)
; Parameters:
; drive number and filename to save to,
; vram bank and address of the bitmap data to save.
; Returns: success status. If false, error_message points to the error message string.
; TODO: how to save bitmaps that are not the full visible screen width (non-contiguous scanlines)?
if compression {
error_message = "compression not supported"
return false
}
error_message = 0
if width!=320 and width!=640 {
error_message = "width not 320 or 640"
goto save_end
}
old_drivenumber = diskio.drivenumber
diskio.drivenumber = drivenumber
if diskio.f_open_w(filename) {
cx16.r0 = diskio.status()
if cx16.r0[0]!='0' {
error_message = cx16.r0
goto save_end
}
diskio.reset_write_channel()
if write_header() {
if write_palette() {
if not write_bitmap(vbank, vaddr)
error_message = "bitmap error"
} else
error_message = "palette error"
} else
error_message = "header error"
} else
error_message = diskio.status()
save_end:
diskio.f_close_w()
diskio.drivenumber = old_drivenumber
return error_message==0
}
sub set_bpp(ubyte bpp) {
ubyte[8] depths = [0,1,1,2,2,2,2,3]
vera_colordepth = depths[bpp-1]
}
sub set_vera_colordepth(ubyte depth) {
vera_colordepth = depth
bitsperpixel = 1 << depth
}
; ------------------- helper routines, usually not needed to call yourself -------------------------
sub read_header() -> bool {
; load a BMX header from the currently active input file
for cx16.r0L in 0 to sizeof(header)-1 {
header[cx16.r0L] = cbm.CHRIN()
}
return not cbm.READST()
}
sub read_palette() -> bool {
; load palette data from the currently active input file
; if palette_buffer_ptr is not 0, the palette data is read into that memory buffer,
; otherwise it is read directly into the palette in vram.
cx16.vaddr(1, $fa00+palette_start*2, 0, 1)
cx16.r3 = palette_buffer_ptr
cx16.r2L = lsb(palette_entries)
do {
cx16.r4L = cbm.CHRIN()
cx16.r4H = cbm.CHRIN()
if cx16.r3 {
pokew(cx16.r3, cx16.r4) ; into memory
cx16.r3+=2
} else {
cx16.VERA_DATA0 = cx16.r4L ; into vram
cx16.VERA_DATA0 = cx16.r4H
}
cx16.r2L--
} until cx16.r2L==0
return cbm.READST()==0 or cbm.READST()&$40 ; no error or eof?
}
sub read_bitmap_padded(ubyte vbank, uword vaddr, uword screenwidth) -> bool {
; load bitmap "stamp" into vram from the currently active input file
cx16.r3 = bytes_per_scanline(width) ; num bytes per image scanline
cx16.r2 = bytes_per_scanline(screenwidth) ; num bytes per screen scanline
repeat height {
cx16.vaddr(vbank, vaddr, 0, 1)
read_scanline(cx16.r3)
vaddr += cx16.r2
if_cs
vbank++
}
return cbm.READST()==0 or cbm.READST()&$40 ; no error or eof?
}
sub read_bitmap(ubyte vbank, uword vaddr) -> bool {
; load contiguous bitmap into vram from the currently active input file
cx16.r3 = bytes_per_scanline(width)
cx16.vaddr(vbank, vaddr, 0, 1)
repeat height
read_scanline(cx16.r3)
return cbm.READST()==0 or cbm.READST()&$40 ; no error or eof?
}
sub read_scanline(uword size) {
while size {
cx16.r0 = cx16.MACPTR(min(255, size) as ubyte, &cx16.VERA_DATA0, true)
if_cs {
; no MACPTR support
repeat size
cx16.VERA_DATA0 = cbm.CHRIN()
return
}
size -= cx16.r0
}
}
sub write_header() -> bool {
; save out the BMX header to the currently active output file
build_header()
for cx16.r0L in 0 to sizeof(header)-1 {
cbm.CHROUT(header[cx16.r0L])
}
return not cbm.READST()
}
sub write_palette() -> bool {
; write palette data to the currently active input file
; if palette_buffer_ptr is not 0, the palette data is read from that memory buffer,
; otherwise it is read directly from the palette in vram.
cx16.r3 = palette_buffer_ptr
cx16.r2L = lsb(palette_entries)
cx16.vaddr(1, $fa00+palette_start*2, 0, 1)
do {
if cx16.r3 {
cbm.CHROUT(@(cx16.r3)) ; from memory
cx16.r3++
cbm.CHROUT(@(cx16.r3))
cx16.r3++
} else {
cbm.CHROUT(cx16.VERA_DATA0) ; from vram
cbm.CHROUT(cx16.VERA_DATA0)
}
cx16.r2L--
} until cx16.r2L==0
return not cbm.READST()
}
sub write_bitmap(ubyte vbank, uword vaddr) -> bool {
; save contiguous bitmap from vram to the currently active output file
cx16.vaddr(vbank, vaddr, 0, 1)
cx16.r3 = bytes_per_scanline(width)
repeat height
write_scanline(cx16.r3)
return not cbm.READST()
sub write_scanline(uword size) {
while size {
cx16.r0L = lsb(size)
if msb(size)
cx16.r0L = 0 ; 256 bytes
cx16.r0 = cx16.MCIOUT(cx16.r0L, &cx16.VERA_DATA0, true)
if_cs {
; no MCIOUT support
repeat size
cbm.CHROUT(cx16.VERA_DATA0)
return
}
size -= cx16.r0
}
}
}
sub bytes_per_scanline(uword w) -> uword {
ubyte[4] shifts = [3,2,1,0]
return w >> shifts[vera_colordepth]
}
sub parse_header() -> bool {
if header[0]==FILEID[0] and header[1]==FILEID[1] and header[2]==FILEID[2] {
if header[3]==1 { ; only version 1 supported for now
bitsperpixel = header[4]
vera_colordepth = header[5]
width = peekw(&header+6)
height = peekw(&header+8)
palette_entries = header[10]
if palette_entries==0
palette_entries=256
palette_start = header[11]
; the data offset is not needed: data_offset = peekw(&header+12)
compression = header[14]
border = header[15]
return true
}
}
return false
}
sub build_header() {
; build the internal BMX header structure
; normally you don't have to call this yourself
sys.memset(header, sizeof(header), 0)
uword data_offset = palette_entries*$0002
data_offset += sizeof(header)
header[0] = FILEID[0]
header[1] = FILEID[1]
header[2] = FILEID[2]
header[3] = 1 ; version 1
header[4] = bitsperpixel
header[5] = vera_colordepth
header[6] = lsb(width)
header[7] = msb(width)
header[8] = lsb(height)
header[9] = msb(height)
header[10] = lsb(palette_entries)
header[11] = palette_start
header[12] = lsb(data_offset)
header[13] = msb(data_offset)
header[14] = compression
header[15] = border
}
}