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95 lines
2.8 KiB
Lua
95 lines
2.8 KiB
Lua
; this program shows the use of the f_seek function to seek to a position in an opened file.
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; (this only works on Commander X16 DOS. on sdcard, not on host filesystem.)
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%import diskio
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%import textio
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%zeropage basicsafe
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%option no_sysinit
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main {
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uword megabuffer = memory("megabuffer", 20000, 256)
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sub start() {
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txt.print("writing data file (drive 8)...\n")
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uword total=0
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if diskio.f_open_w("@:seektestfile.bin") {
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repeat 100 {
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str text = "hello world.*"
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void diskio.f_write(text, string.length(text))
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total += string.length(text)
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}
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diskio.f_close_w()
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txt.print("written size=")
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txt.print_uw(total)
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txt.nl()
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} else {
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txt.print("error: ")
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txt.print(diskio.status())
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sys.exit(1)
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}
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read_last_bytes()
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; NOTE: f_seek_w() doesn't work reliably right now. I only manage to corrupt the fat32 filesystem on the sdcard with it...
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; txt.print("\nseeking to 1292 and writing a few bytes...\n")
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; if diskio.f_open_w("seektestfile.bin,p,a") {
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; diskio.f_seek_w(0, 1292)
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; void diskio.f_write("123", 3)
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; diskio.f_close_w()
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; } else {
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; txt.print("error: ")
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; txt.print(diskio.status())
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; sys.exit(1)
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; }
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read_last_bytes()
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}
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sub read_last_bytes() {
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; read the last 10 bytes of the 1300 bytes file
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uword total = 0
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uword size
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txt.print("\nreading...\n")
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if diskio.f_open("seektestfile.bin") {
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size = diskio.f_read_all(megabuffer)
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diskio.f_close()
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txt.print("size read:")
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txt.print_uw(size)
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txt.nl()
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} else {
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txt.print("error!\n")
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sys.exit(1)
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}
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txt.print("\nseeking to 1290 and reading...\n")
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if diskio.f_open("seektestfile.bin") {
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diskio.f_seek(0, 1290)
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uword ptr = megabuffer
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do {
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size = diskio.f_read(ptr, 255)
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total += size
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ptr += size
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} until size==0
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diskio.f_close()
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txt.print("size read=")
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txt.print_uw(total)
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txt.nl()
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megabuffer[lsb(total)] = 0
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txt.print("buffer read=")
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ubyte idx
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for idx in 0 to lsb(total-1) {
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txt.print_ubhex(megabuffer[idx], false)
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txt.spc()
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}
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txt.print("\nas text: \"")
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txt.print(megabuffer)
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txt.print("\"\n")
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} else {
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txt.print("error: ")
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txt.print(diskio.status())
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sys.exit(1)
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}
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}
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}
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