Function call with string params bug (*solved*)

[britlion]

I think there's still a bug in the string slicing.

I was playing with the print64 routine - and I think it works just fine, but when printing sliced strings it breaks.

Code:

SUB printat64 (y as uByte, x as uByte) POKE @p64coords,x POKE @p64coords+1,y END sub SUB print64 (characters$ as String) asm LD L,(IX+4) LD H,(IX+5) ; Get String address of characters$ into HL. ; Load BC with length of string, and move HL to point to first character. ld c, (hl) ; 60020 78 inc hl ; 60021 35 ld b, (hl) ; 60022 70 inc hl ; 60023 35 ; Test string length. If Zero, exit. ld a, c ; 60024 121 or b ; 60025 176 jp z, p64_END ; 60026 200 examineChar: ld a, (hl) ; Grab the character cp 128 ; too high to print? jr nc, nextChar ; then we go to next. cp 22 ; Is this an AT? jr nz, newLine ; If not, hop to newLine routine. ex de, hl ; Swap DE and HL and a ; Clear Carry ld hl, 2 ; sbc hl, bc ; Can we Shorten our string length by 2? If not then at (y,x) doesn't make sense. ex de, hl ; Swap DE and HL back jp nc, p64_END ; If we went negative, there wasn't anything to AT to, so we return. inc hl ; Onto our Y co-ordinate ld d, (hl) ; And load it into D dec bc ; Shorten our remaining string counter. inc hl ; Onto the X Co-ordinate ld e, (hl) ; Load it into E dec bc ; Shorten our remaining string counter call p64_test_X ; Make xy legal 60051 205 53 235 jr p64_eaa3 ; Go to save coords 60054 24 11 newLine: cp 13 ; Is this a newline character? 60056 254 13 jr nz, p64_isPrintable ; If not, hop to testing to see if we can print this 60058 32 13 ld de, (p64_coords) ; Get coords 60060 237 91 68 235 call p64_nxtLine ; Go to next line. ; 60064 205 58 235 p64_eaa3: ld (p64_coords), de ; 60067 237 83 68 235 jr nextChar ; 60071 24 11 p64_isPrintable: cp 31 ; Bigger than 31? 60073 254 31 jr c, nextChar ; If not, get the next one. 60075 56 7 push hl ; Save position 60077 229 push bc ; Save Count 60078 197 call p64_PrintChar ; Call Print SubRoutine 60079 205 189 234 pop bc ; Recover length count 60082 193 pop hl ; Recover Position 60083 225 nextChar: inc hl ; Point to next character 60084 35 dec bc ; Count off this character 60085 11 ld a, b ; Did we run out? 60086 120 or c ; 60087 177 jr nz, examineChar ; If not, examine the next one 60088 32 193 jp p64_END ; Otherwise hop to END. 60090 201 ;p64_eabb: ; defb "z$" ;Original "basic" accessed routine used this variable. ;ld a, d ; 60091 122 ;inc h ; 60092 36 ;p64_eabd: p64_PrintChar: exx ; 60093 217 push hl ; Save HL' 60094 229 exx ; 60095 217 sub 32 ; Take out 32 to convert ascii to position in charset 60096 214 32 ld h, 0 ; 60098 38 0 rra ; Divide by 2 60100 31 ld l, a ; Put our halved value into HL 60101 111 ld a, 240 ; Set our mask to LEFT side 60102 62 240 jr nc, p64_eacc ; If we didn't have a carry (even #), hop forward. 60104 48 2 ld a, 15 ; If we were ab idd #, set our mask to RIGHT side instead 60106 62 15 p64_eacc: add hl, hl ; 60108 41 add hl, hl ; 60109 41 add hl, hl ; Multiply our char number by 8 60110 41 ld de, p64_charset ; Get our Charset position 60111 17 70 235 add hl, de ; And add our character count, so we're now pointed at the first byte of the right character. 60114 25 exx ; 60115 217 ld de, (p64_coords) ; 60116 237 91 68 235 ex af, af' ; 60120 8 call p64_loadAndTest ; 60121 205 49 235 ex af, af' ; 60124 8 inc e ; 60125 28 ld (p64_coords), de ; Put position+1 into coords 60126 237 83 68 235 dec e ; 60130 29 ld b, a ; 60131 71 rr e ; Divide X position by 2 60132 203 27 ld c, 0 ; 60134 14 0 rl c ; Bring carry flag into C (result of odd/even position) 60136 203 17 and 1 ; Mask out lowest bit in A 60138 230 1 xor c ; XOR with C (Matches position RightLeft with Char RightLeft) 60140 169 ld c, a ; 60141 79 jr z, p64_eaf6 ; If they are both the same, skip rotation. 60142 40 6 ld a, b ; 60144 120 rrca ; 60145 15 rrca ; 60146 15 rrca ; 60147 15 rrca ; 60148 15 ; Move the mask to the other half of the byte. ld b, a ; 60149 71 p64_eaf6: ld a, d ; Get Y coord 60150 122 sra a ; 60151 203 47 sra a ; 60153 203 47 sra a ; Multiply by 8 60155 203 47 add a, 88 ; 60157 198 88 ld h, a ; Put high byte value for attribute into H. 60159 103 ld a, d ; 60160 122 and 7 ; 60161 230 7 rrca ; 60163 15 rrca ; 60164 15 rrca ; 60165 15 add a, e ; 60166 131 ld l, a ; Put low byte for attribute into l 60167 111 ld a, (23693) ; Get permanent Colours from System Variable 60168 58 141 92 ld (hl), a ; Write new attribute 60171 119 ld a, d ; 60172 122 and 248 ; 60173 230 248 add a, 64 ; 60175 198 64 ld h, a ; 60177 103 ld a, b ; 60178 120 cpl ; 60179 47 ld e, a ; 60180 95 exx ; 60181 217 ld b, 8 ; 60182 6 8 p64_eb18: ld a, (hl) ; 60184 126 exx ; 60185 217 bit 0, c ; 60186 203 65 jr z, p64_eb22 ; 60188 40 4 rrca ; 60190 15 rrca ; 60191 15 rrca ; 60192 15 rrca ; 60193 15 p64_eb22: and b ; 60194 160 ld d, a ; 60195 87 ld a, (hl) ; 60196 126 and e ; 60197 163 or d ; 60198 178 ld (hl), a ; 60199 119 inc h ; 60200 36 exx ; 60201 217 inc hl ; 60202 35 djnz p64_eb18 ; 60203 16 235 exx ; 60205 217 pop hl ; 60206 225 exx ; 60207 217 ret ; 60208 201 p64_loadAndTest: ld de, (p64_coords) ; 60209 237 91 68 235 ; SubRoutine to go to legal character position. (60213) p64_test_X: ld a, e ; Get column from e cp 64 ; more than 64 ? jr c, p64_test_Y ; If not, then jump over nextline p64_nxtLine: inc d ; Move down 1 ld e, 0 ; reset x co-ord to zero p64_test_Y: ld a, d ; get Y co-ord cp 24 ; Past 24? ret c ; Return if not. ld d, 0 ; Rest y co-ord to top of screen. ret ; Return. end asm p64coords: asm p64_coords: defb 64; X Coordinate store 60228 64 defb 23; Y Coordinate Store 60229 23 p64_charset: ; 60230 DEFB 0,2,2,2,2,0,2,0 ; Space ! DEFB 0,80,82,7,2,7,2,0 ; " # DEFB 0,37,113,66,114,20,117,32 ; $ % DEFB 0,34,84,32,96,80,96,0 ; & ' DEFB 0,36,66,66,66,66,36,0 ; ( ) DEFB 0,0,82,34,119,34,82,0 ; * + DEFB 0,0,0,0,7,32,32,64 ; , - DEFB 0,1,1,2,2,100,100,0 ; . / DEFB 0,34,86,82,82,82,39,0 ; 0 1 DEFB 0,34,85,18,33,69,114,0 ; 2 3 DEFB 0,87,84,118,17,21,18,0 ; 4 5 DEFB 0,55,65,97,82,84,36,0 ; 6 7 DEFB 0,34,85,37,83,85,34,0 ; 8 9 DEFB 0,0,2,32,0,34,2,4 ; : ; DEFB 0,0,16,39,64,39,16,0 ; < = DEFB 0,2,69,33,18,32,66,0 ; > ? DEFB 0,98,149,183,181,133,101,0 ; @ A Changed from ;0,2,37,87,117,85,53,0 DEFB 0,98,85,100,84,85,98,0 ; B C DEFB 0,103,84,86,84,84,103,0 ; D E DEFB 0,114,69,116,71,69,66,0 ; F G DEFB 0,87,82,114,82,82,87,0 ; H I DEFB 0,53,21,22,21,85,37,0 ; J K DEFB 0,69,71,71,69,69,117,0 ; L M DEFB 0,82,85,117,117,85,82,0 ; N O DEFB 0,98,85,85,103,71,67,0 ; P Q DEFB 0,98,85,82,97,85,82,0 ; R S DEFB 0,117,37,37,37,37,34,0 ; T U DEFB 0,85,85,85,87,39,37,0 ; V W DEFB 0,85,85,37,82,82,82,0 ; X Y DEFB 0,119,20,36,36,68,119,0 ; Z [ DEFB 0,71,65,33,33,17,23,0 ; \ ] DEFB 0,32,112,32,32,32,47,0 ; ^ _ DEFB 0,32,86,65,99,69,115,0 ; £ a DEFB 0,64,66,101,84,85,98,0 ; b c DEFB 0,16,18,53,86,84,35,0 ; d e DEFB 0,32,82,69,101,67,69,2 ; f g DEFB 0,66,64,102,82,82,87,0 ; h i DEFB 0,20,4,53,22,21,85,32 ; j k DEFB 0,64,69,71,71,85,37,0 ; l m DEFB 0,0,98,85,85,85,82,0 ; n o DEFB 0,0,99,85,85,99,65,65 ; p q DEFB 0,0,99,84,66,65,70,0 ; r s DEFB 0,64,117,69,69,85,34,0 ; t u DEFB 0,0,85,85,87,39,37,0 ; v w DEFB 0,0,85,85,35,81,85,2 ; x y DEFB 0,0,113,18,38,66,113,0 ; z { DEFB 0,32,36,34,35,34,36,0 ; | { DEFB 0,6,169,86,12,6,9,6 ; ~ (c) p64_END: end asm end sub DIM n,x,y as uInteger CLS FOR n=1 to 10000 y=rnd*23 x=rnd*63 printat64(y, x) print64 ("ABCDEFGHIJKLMNOPQRSTUVWXYZ"(n MOD 26 TO n MOD 26)) 'print64 ("A") print at 23,0;n;" y:";y;" x:";x;" L:";n NEXT n END

If you swap the two print lines at the end (line 254 and 255), if you have print "string" (slice) it prints 951 characters and then explodes.

If instead you just have print64("A") it completes (though exits with a drive not ready error, which is odd).

I think that something in the string slicing is making it go weird.

Thoughts?

[boriel]

If you use only print64("A") and your program exits with a "Drive not ready" error, then something is corrupted. It must always exit with an "OK" message. I've run such test, and it exits with an "Ok" in my case. :?: :?:

It seems there's a memory leak somewhere, but still don't know whether it's in your routine or in my one. Recompiling your program with --debug-memory flag triggers the "Out of memory" error. On the other hand, using just PRINT works ok. :?

Note: a string might also be passed as a NULL (HL = 0), specially when there's been not enough memory (which is the case). Your routine should also check that case before taking BC (Length) from (HL) and (HL + 1)

The following also crashes:

Code:

tmp$ = "1" print64("A" + tmp$)

This means the temporary string "A1" is not being freed from memory. This could be your routine or the compilers routines. Will investigate further...

Update: It's the compiler. :oops: The routine "free string on return" is not doing so... Fixing... :|
Update II: Seems to be fixed now. It wasn't the STRSLICE routine, but a lowlevel backend instruction for passing temporary strings to functions in args (as you did). Please download new rev1713 from the download page and tell me if it works now (I does work to me)

[britlion]

Wow.

You are amazing at bug squising. And fast - I'd have been lost.

Yes, it now compiles, runs all the way, and exits cleanly.

Which means - even though it's been sitting there for 4 months, there's a working 64 character print routine to add to the library.

[boriel]

I also agree this should be in the next release. I like it. Also, will clear commented code and added HL==0 test at the beginning.
If the programmer does not use PRINT it won't be included in the resulting program, and s/he can use print64 or print42 instead.