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Text File | 2006-10-19 | 23.8 KB | 975 lines

* I/O Opcode 2 - READ * * This routine will store the next record of the specified file * in the user's buffer provided * 1. The file is open * 2. We have not reached end of file yet * * Once it determines that the file is open and not at end of file, * it must determine if the contents of the buffer is valid. If not, * it will read the next sector from the disk. If convient, it will * read 2 sectors and use all 512 bytes of the buffer. * * Date: April 22, 1995 * Author: David Nieters * * Well, it's less than one week till Lima and I'm still writing * new code. Let's home I get some of this working in time so it * looks like it's 90% done like Don has been telling everybody. * * Modification History * * November 20, 1995 - Fixed directory file access to return the * exact length for each filename instead of padded with * spaces. Also, returns a null string when reached the * end instead of 10 spaces. Will add subdirectory listings * later. * READ0 ANDI R12,>FF00 AI R12,24 LDCR @B02,4 Select RAM bank 2 BLWP @IFO Check to make sure file is open JEQ READ2 READ1 BL @DSRERR DATA >0700 File error READ2 CB @56(R5),@B02 See if file has been opened for reading JEQ READ3 CB @56(R5),@ZERO or update access JEQ READ3 CB @56(R5),@B05 Or directory access JEQ READ3A BL @DSRERR DATA >0200 Bad open attribute? READ3A B @READ60 Handle directory read READ4 B @READ50 Handle the relative read READ3 LDCR @ZERO,4 Check for sequential access MOVB @PABBUF+1,R1 Get flags ANDI R1,>0100 JNE READ4 LDCR @B02,4 * We know that the file is open and we are reading sequentially. * Now check to see if we're at end of file. * MOV @4(R5),R1 Get FDR address MOV @62(R5),R2 Get sector/record number MOV @54(R5),R3 Get the pointer within the buffer LDCR @2(R5),4 Select BANK with FDR * If the file is empty, we must be reading * past the end of file. C @ZERO,@18(R1) JEQ READ5 SWPB R2 C R2,@18(R1) See if we're in the last sector written JNE READ7 * Here we check for fixed or variable length records. If fixed, * the value in R2 was the last record written and we know we're * at the end of the file. It the records are variable length, we * check to see if we're pointing to an end of sector marker. * MOVB @12(R1),R0 Check for fixed or variable length ANDI R0,>8000 JNE READ6 READ5 LDCR @B02,4 Close file if attempting to CLR @4(R5) read past end of file BL @DSRERR DATA >0500 Attempt to read past end of file READ6 LDCR @B02,4 Select RAM bank 2 LDCR @3(R5),4 Select bank with buffer CB *R3,@B255 Are we at the end of the sector? JEQ READ5 READ7 LDCR @B02,4 Select RAM bank 2 C @50(R5),@ZERO Have we read the 1st sector yet? JNE READ20 * We have to read in the 1st sector of the file * LDCR @2(R5),4 Select bank with the FDR in it MOV @40(R1),R7 Get 1st AU allocate in file LDCR @B02,4 Select RAM bank 2 MOV R7,@50(R5) Save current AU CLR @52(R5) We're reading 1st sector if this AU CLR @58(R5) Set buffer size to 256 for now MOV @6(R5),@54(R5) Set pointer to beginning of buffer LDCR @B04,4 Select RAM bank 4 MOV R6,R3 SRL R3,8 SLA R3,1 MOV @SAUTBL(R3),R3 Get the Sectors/AU for this disk MPY R3,R7 LI R1,SECBUF SRL R8,1 JNC READ8 AI R1,>100 READ8 SRL R7,1 JNC READ9 AI R8,>8000 READ9 LDCR @ZERO,4 BLWP @BANKIT DATA SCSIRD JEQ READ10 BL @DSRERR DATA >0600 Device error * Now that we have read the block from the disk, see if we * can use all 512 bytes, or only 256 * READ10 LDCR @B02,4 Select RAM bank 2 CI R3,2 Make sure Sectors/AU > 1 JL READ11 CI R1,SECBUF Make sure we start at beginning JNE READ11 SETO @58(R5) We're using all 512 bytes! READ11 MOV @6(R5),R2 Get buffer address MOVB @3(R5),R3 Get buffer bank number READ12 LDCR @ZERO,4 Select RAM bank 0 MOV *R1+,R0 LDCR R3,4 MOV R0,*R2+ CI R1,SECBUF+512 JNE READ12 LDCR @B02,4 Select RAM bank 2 MOV @4(R5),R1 Get FDR address LDCR @2(R5),4 MOVB @12(R1),R0 Set sector # to 1 if a variable file ANDI R0,>8000 JEQ READ13 LDCR @B02,4 INC @62(R5) READ13 B @READ40 ***************************************************** * * Here we want to check to see if the buffer is * valid. If it is not, then we must read the * next sector into the buffer. * ***************************************************** READ20 LDCR @B02,4 Select RAM bank 2 MOV @4(R5),R1 Get pointer FDR LDCR @2(R5),4 MOVB @12(R1),R2 Get file flags LDCR @B02,4 Select RAM bank 2 ANDI R2,>8000 See if we have fixed length records JNE READ2C B @READ39 READ2C MOV @54(R5),R1 Get pointer in buffer LDCR @3(R5),4 Select bank with buffer in it CB *R1,@B255 If it starts with >FF, it's end of sector JEQ READ2B B @READ40 READ2B LDCR @B02,4 Select RAM bank 2 INC @62(R5) Increment sector number * We're at the end of the sector. If we have a 512 byte buffer and * we're still in the first 256 bytes, just go to second half of * buffer. Otherwise, read the next sector from the disk. * READ21 LDCR @B02,4 Select RAM bank 2 C @58(R5),@ZERO See if we have a 512 byte buffer JEQ RD21A MOV @54(R5),R1 See if we're in 1st half of buffer ANDI R1,>0100 JNE RD21A MOV @54(R5),R1 OK, just go to next half ANDI R1,>FF00 AI R1,>100 MOV R1,@54(R5) Save new pointer INC @52(R5) Increment sector counter LDCR @B04,4 Select RAM bank 4 MOV R6,R3 SRL R3,8 SLA R3,1 MOV @SAUTBL(R3),R3 LDCR @B02,4 Select RAM bank 2 C R3,@52(R5) See if we transcended an AU boundry JNE RD21B CLR @52(R5) Clear sector within AU INC @50(R5) increment AU number RD21B B @READ40 * Well, it looks like we're going to have to read the * next sector from disk * RD21A LDCR @B04,4 Select RAM bank 4 MOV R6,R3 SRL R3,8 SLA R3,1 MOV @SAUTBL(R3),R3 LDCR @B02,4 Select RAM bank 2 MOV @50(R5),R7 Get current AU INC @52(R5) go to next sector within AU C @52(R5),R3 See if we need to go to next AU JNE READ25 * If this was the last AU in the cluster, we must go * to the next cluster. Otherwise, just increment * the current AU. CLR @52(R5) MOV @4(R5),R1 Get FDR address LDCR @2(R5),4 Select bank with FDR LI R10,54 There are 54 total clusters/FDR AI R1,42 READ22 MOV *R1+,R2 JEQ READ23 C R2,R7 JEQ READ24 INCT R1 DEC R10 JNE READ22 READ23 INC R7 JMP READ25 READ24 MOV *R1,R7 READ25 LDCR @B02,4 Select RAM bank 2 MOV R7,@50(R5) Save current AU MOV @6(R5),@54(R5) Reset pointer in buffer CLR @58(R5) Set buffer size to 256 byte (for now) MPY R3,R7 A @52(R5),R8 Add in sector within AU JNC READ26 INC R7 READ26 LI R1,SECBUF SRL R8,1 JNC READ27 AI R1,>100 READ27 SRL R7,1 JNC READ28 AI R8,>8000 READ28 LDCR @ZERO,4 Select RAM bank 0 BLWP @BANKIT Read the sector from disk DATA SCSIRD JEQ READ29 BL @DSRERR DATA >0600 Device error READ29 LDCR @B02,4 CI R3,2 See if we can use a 512 byte buffer JL RD29A CI R1,SECBUF JNE RD29A SETO @58(R5) RD29A MOV @6(R5),R2 Get buffer address MOVB @3(R5),R4 READ30 LDCR @ZERO,4 Select RAM bank 0 MOV *R1+,R10 LDCR R4,4 MOV R10,*R2+ CI R1,SECBUF+512 JNE READ30 JMP READ40 R21HLP B @RD21A Help the JH instruction below R22HLP B @READ21 * If we are handling fixed length records, we handle the * buffer validity a little differently. Here goes * If the pointer is exactly >200 greater than the base, * we know we have to read the next sector. If it is * exactly >100 greater than the base and the buffer size * is 256 bytes, we have to read the next sector. READ39 LDCR @B02,4 Select RAM bank 2 MOV @54(R5),R1 Get pointer within buffer S @6(R5),R1 Subtract the base address CI R1,>200 JEQ R21HLP CI R1,>100 JNE RD39A C @58(R5),@ZERO See if buffer size is 256 JEQ R21HLP If so, read next sector INC @52(R5) RD39A MOV @54(R5),R1 Get pointer within buffer ANDI R1,>00FF MOV @4(R5),R2 Get FDR address LDCR @2(R5),4 Select bank with FDR MOVB @17(R2),R4 Get record length SRL R4,8 A R4,R1 See if we can add record length CI R1,>0100 Without going over JH R22HLP If not, read next sector * We know the buffer is good. All we have to do now is * transfer the record to the user's buffer. READ40 * If we have a fixed length record, read that many bytes. * If we have a variable length record, read the length * byte first and read that many bytes. * LDCR @B02,4 Select RAM bank 2 MOV @54(R5),R2 Get buffer pointer MOVB @3(R5),R3 Get buffer bank MOV @4(R5),R1 Get Address of FDR LDCR @2(R5),4 Select bank where FDR is MOVB @12(R1),R0 ANDI R0,>8000 Mask out fixed/variable bit JEQ READ44 * Well, we have a variable length record. Read the record * size byte and store that many characters in the user's * buffer. * LDCR R3,4 MOVB *R2+,R0 READ41 LDCR @ZERO,4 Store record size in user's PAB MOV @PABADR,R1 ORI R1,>4000 AI R1,5 SWPB R1 MOVB R1,@VDPWA SWPB R1 MOVB R1,@VDPWA NOP MOVB R0,@VDPWD JEQ READ43 Skip copy if a null record SRL R0,8 * Set the VDP write address to the user's buffer * MOV @PABBUF+2,R1 ORI R1,>4000 SWPB R1 MOVB R1,@VDPWA SWPB R1 MOVB R1,@VDPWA LDCR R3,4 READ42 MOVB *R2+,@VDPWD DEC R0 JNE READ42 READ43 LDCR @B02,4 MOV R2,@54(R5) LDCR @ZERO,4 B @DSRRT READ44 MOVB @17(R1),R0 Get fixed record length LDCR @B02,4 Select RAM bank 2 INC @62(R5) Increment last record # read. JMP READ41 READ49 BL @DSRERR DATA >0500 Attempt to read past end of file ** * * Here is where we handle relative access reads. The trick involves * several divisions to compute where the record fits in the file. * ** READ50 BL @POSIT LDCR @ZERO,4 MOV @PABADR,R1 Increment record # in caller's PAB ORI R1,>4000 AI R1,6 SWPB R1 MOVB R1,@VDPWA SWPB R1 MOVB R1,@VDPWA MOV @PABBUF+6,R1 INC R1 MOVB R1,@VDPWD SWPB R1 MOVB R1,@VDPWD B @READ40 Transfer record to user and return ** * * Here is where we handle directory reads. Record 0 is the * directory itself. Records 1-127 are files. * ** READ60 * Store the # of characters written in the caller's PAB * LDCR @ZERO,4 Select RAM bank 0 MOV @PABADR,R1 ORI R1,>4000 AI R1,5 SWPB R1 MOVB R1,@VDPWA SWPB R1 MOVB R1,@VDPWA LI R0,38*256 Store record length MOVB R0,@VDPWD * Set the VDP write address to the user's buffer * MOV @PABBUF+2,R1 ORI R1,>4000 SWPB R1 MOVB R1,@VDPWA SWPB R1 MOVB R1,@VDPWA * See which record we are reading * MOVB @PABBUF+1,R1 ANDI R1,>0100 JEQ READ61 MOV @PABADR,R1 Increment record # in caller's PAB ORI R1,>4000 AI R1,6 SWPB R1 MOVB R1,@VDPWA SWPB R1 MOVB R1,@VDPWA MOV @PABBUF+6,R1 INC R1 MOVB R1,@VDPWD SWPB R1 MOVB R1,@VDPWD MOV @PABBUF+2,R1 ORI R1,>4000 SWPB R1 MOVB R1,@VDPWA SWPB R1 MOVB R1,@VDPWA MOV @PABBUF+6,R1 JMP READ62 READ61 LDCR @B02,4 Sequential read, get from cache MOV @62(R5),R1 INC @62(R5) READ62 CI R1,0 See if reading directory JNE READ70 * Copy the directory name to the user's buffer * LDCR @B02,4 MOV @4(R5),R4 LDCR @2(R5),4 LI R0,10 AI R4,9 READ63 CB *R4,@SPACE JNE RD63A DEC R4 DEC R0 JNE READ63 RD63A SWPB R0 MOVB R0,@VDPWD Set name length JEQ RD63C SWPB R0 S R0,R4 INC R4 RD63B MOVB *R4+,@VDPWD DEC R0 JNE RD63B RD63C * Now get the rest of the info * R8 = Record type (Always zero) * R9 = Total # of AU's on the disk * R10 = # of free AU's on the disk * Now get the number of free AU's on the disk. We read the * entire bitmap from disk and count the number of zeros. * There's got to be a better way to do this, and when I * think of it, I'll change this code. * CLR R7 CLR R8 LI R4,SECBUF+>100 The bitmap is right after VIB CLR R10 R10 Keeps track of # of free AU's LDCR @ZERO,4 READ64 BLWP @BANKIT DATA SCSIRD JEQ READ65 AI R8,16 If error, read copy BLWP @BANKIT DATA SCSIRD AI R8,-16 READ65 * If the value is 0, we can just add 16 to the number of * free AU's. Otherwise, we have to count the bits in R1. * If we just read the VIB, get the disk size here CI R8,0 JNE RD65A MOV @SECBUF+10,R5 Save in R5 for now MOV @SECBUF+16,R2 Get sectors/AU SRL R2,12 INC R2 RD65A MOV *R4+,R1 JNE READ68 AI R10,16 READ66 CI R4,SECBUF+>200 JNE RD65A READ67 LI R4,SECBUF INC R8 CI R8,16 JNE READ64 * Now report the disk size and free space. We use * the new 20 bit integer routine for this! MOV R2,R9 Store Sectors/AU in another REG CLR R1 File type = 0 CLR R2 BL @I20TOR MOV R5,R1 Disk size in AU's MPY R9,R1 BL @I20TOR MOV R10,R1 MPY R9,R1 BL @I20TOR LDCR @ZERO,4 B @DSRRT READ68 CI R1,-1 JEQ READ66 LI R0,16 READ69 SLA R1,1 JOC RD69A INC R10 RD69A DEC R0 JNE READ69 JMP READ66 * READ80 We're past all the filenames, return * information on subdirectories now. * READ80 S R3,R1 Subtract # of files MOVB @23(R2),R3 Get # of subdirectories SRL R3,8 C R1,R3 JH READ81 B @READ91 READ81 CLR @VDPWD String length LI R1,3 Return 3 RAXID 100 numbers LI R2,>0808 READ82 MOV R2,@VDPWD LI R3,8 READ83 CLR @VDPWD DEC R3 JNE READ83 DEC R1 JNE READ82 LDCR @ZERO,4 B @DSRRT ** * * Here we are retrieving information about a file. If the * record number is out of range, return all zeros. * ** READ70 LDCR @B02,4 MOV @4(R5),R2 Get DDR address LDCR @2(R5),4 MOVB @22(R2),R3 Get # of files in directory SRL R3,8 C R1,R3 JH READ80 * See if the FDIR has been loaded into the buffer. If it * hasn't, read it in now MOV @24(R2),R7 Get AU of FDIR just in case LDCR @B02,4 C @58(R5),@ZERO JNE READ75 SETO @58(R5) Set flag MOV R6,R3 Read FDIR SRL R3,8 SLA R3,1 LDCR @B04,4 MPY @SAUTBL(R3),R7 LI R2,SECBUF SRL R8,1 JNC READ71 AI R2,>100 READ71 SRL R7,1 JNC READ72 AI R8,>8000 READ72 LDCR @ZERO,4 BLWP @BANKIT DATA SCSIRD JEQ READ73 BL @DSRERR DATA >0600 READ73 LDCR @B02,4 MOV @6(R5),R3 Get buffer address MOVB @3(R5),R4 Get buffer Bank LI R0,256 READ74 LDCR @ZERO,4 MOV *R2+,R7 LDCR R4,4 MOV R7,*R3+ DECT R0 JNE READ74 READ75 DEC R1 SLA R1,1 LDCR @B02,4 MOV @6(R5),R4 Get address of buffer LDCR @3(R5),4 A R1,R4 MOV *R4,R7 Get AU of FDR LI R1,SECBUF MOV R6,R3 SRL R3,8 SLA R3,1 LDCR @B04,4 MPY @SAUTBL(R3),R7 SRL R8,1 JNC READ76 AI R1,>100 READ76 SRL R7,1 JNC READ77 AI R8,>8000 READ77 LDCR @ZERO,4 BLWP @BANKIT DATA SCSIRD JEQ READ78 BL @DSRERR DATA >0600 READ78 LI R0,10 Copy filename to user's buffer MOV R1,R9 AI R1,9 RD78A CB *R1,@SPACE JNE RD78B DEC R1 DEC R0 JNE RD78A RD78B SWPB R0 MOVB R0,@VDPWD File length shouldn't be zero JEQ RD79Z but just in case... SWPB R0 MOV R9,R1 READ79 MOVB *R1+,@VDPWD DEC R0 JNE READ79 RD79Z MOV R9,R1 MOV @14(R1),R9 # of sectors allocated MOVB @17(R1),R10 # of bytes/record SRL R10,8 * Now see what type of file it is. We return the following * * 1: Display/Fixed * 2: Display/Variable * 3: Internal/Fixed * 4: Internal/Variable * 5: Program file * * If the file is protected, these numbers are inverted LI R8,5 MOVB @12(R1),R0 ANDI R0,>0100 Check for program file JNE RD79B LI R8,1 Assume Display/Fixed MOVB @12(R1),R0 ANDI R0,>8000 Check for variable records JEQ RD79A INC R8 RD79A MOVB @12(R1),R0 ANDI R0,>0200 Check for internal JEQ RD79B INCT R8 RD79B * Now check to see if the file is protected MOV @12(R1),R0 COC @PROBIT,R0 JNE RD79C NEG R8 RD79C * Now we just have to convert some 16 bit integers to radix 100 * format and store in the user's buffer and go home. * READ90 MOV R8,R2 BL @ITORAD MOV R9,R2 BL @ITORAD MOV R10,R2 BL @ITORAD LDCR @ZERO,4 B @DSRRT ** * * READ91 - Here we return information on a subdirectory * ** READ91 DEC R1 SLA R1,1 LDCR @B02,4 MOV @4(R5),R4 Get address of DDR LDCR @2(R5),4 A R1,R4 MOV @28(R4),R7 Get AU of subdirectory DDR LI R1,SECBUF MOV R6,R3 SRL R3,8 SLA R3,1 LDCR @B04,4 MPY @SAUTBL(R3),R7 SRL R8,1 JNC READ92 AI R1,>100 READ92 SRL R7,1 JNC READ93 AI R8,>8000 READ93 LDCR @ZERO,4 BLWP @BANKIT DATA SCSIRD JEQ READ94 BL @DSRERR DATA >0600 READ94 LI R0,10 See how long the name is MOV R1,R9 AI R1,9 READ95 CB *R1,@SPACE JNE READ96 DEC R1 DEC R0 JNE READ95 READ96 SWPB R0 MOVB R0,@VDPWD Store directory name length JEQ READ98 SWPB R0 MOV R9,R1 READ97 MOVB *R1+,@VDPWD DEC R0 JNE READ97 READ98 MOV R9,R1 LI R8,6 File type = 6 for directory LI R9,2 Size = 2 for now CLR R10 Record size = 0? JMP READ90 ************************************************************ * * * PROCEDURE ITORAD * * * * This procedure will take an unsigned integer stored in * * R1 and convert it to RADIX 100 and store the result in * * the file buffer. * * * ************************************************************ ITORAD MOVB @B08,@VDPWD Store field length (8 bytes) CI R2,0 JEQ ITOR00 CI R2,100 JL ITOR1 CI R2,10000 JL ITOR3 * If it is greater than 65530, assume it's negative CI R2,65530 JL ITOR50 * NEG R2 * ORI R2,>4000 * NEG R2 ANDI R2,>BFFF MOVB R2,@VDPWD SWPB R2 MOVB R2,@VDPWD JMP ITOR1A * Here we are converting a number in the range of 10000-65535 * ITOR50 CLR R1 ITOR5A MOVB @HEX42,@VDPWD LI R0,4 ITOR5B LI R3,10000 DIV R3,R1 SWPB R1 MOVB R1,@VDPWD CLR R1 LI R3,100 DIV R3,R1 SWPB R1 MOVB R1,@VDPWD SWPB R2 MOVB R2,@VDPWD JMP ITOR2 * Here we are doing the number 0 * ITOR00 LI R0,8 JMP ITOR2 * Here are are converting a number in the range of 0-99 * ITOR1 MOVB @HEX40,@VDPWD SWPB R2 MOVB R2,@VDPWD ITOR1A LI R0,6 ITOR2 CLR @VDPWD DEC R0 JNE ITOR2 RT * Here we are converting a number in the range of 100-9999 * ITOR3 MOVB @HEX41,@VDPWD LI R0,5 ITOR3A CLR R1 LI R3,100 DIV R3,R1 SWPB R1 MOVB R1,@VDPWD SWPB R2 MOVB R2,@VDPWD JMP ITOR2 ************************************************************ * * * I20TOR - Convert 20 bit integer to RADIX 100 * * * * This procedure will convert a 20 bit integer to RADIX * * 100 format. The maximum size of a 20 bit integer is * * 1,048,575. * * * * Input: R1, R2 = 20 bit integer (high 12 bits of R1 * * must be zero). * * * * Uses: R0, R1, R2, R3 * * * ************************************************************ I20TOR MOVB @B08,@VDPWD Store field length (8 bytes) CI R1,0 JNE I20TO2 CI R2,0 JEQ ITOR00 Number is zero CI R2,100 JL ITOR1 Number is 1-99 CI R2,10000 JL ITOR3 Number is 100-9999 JMP ITOR5A Number is 10000-65535 I20TO2 * OK. The number is greater than 65535. See if it's * less than 1,000,000 * CI R1,15 JL ITOR5A Number is < 983,040 CI R2,16960 JL ITOR5A ** * * Here we handle numbers 1,000,000-1,048,575 * ** I20TO5 MOVB @HEX43,@VDPWD LI R0,3 MOVB @B01,@VDPWD CLR R1 AI R2,-16960 JMP ITOR5B HEX40 BYTE >40 HEX41 BYTE >41 HEX42 BYTE >42 HEX43 BYTE >43