Looking for some help with code for scrolling up / down through buffer
Don M
Posts: 1,654
Let's say I have a 2048 byte buffer that I dump messages into. Each message would end with an "03" (ETX) byte. Now I want to display them. I know I can do a repeat loop with indexing and an if statement to catch the 03 and stop going forward through. That part I understand.
But let's say I was scrolling forward and now I want to go backward a message at a time. How would that be done?
Any sample code or examples out there?
But let's say I was scrolling forward and now I want to go backward a message at a time. How would that be done?
Any sample code or examples out there?
Comments
There is some sample data in the DAT section. Each line in the DAT section has a start character STX (02), the message, CR / LF and an ETX character (03). The data message in the DAT section is stored into a buffer called "message". I made 2 other buffers that store the charcter index position of each STX and ETX. These are marked in the code.
What I'm trying to simulate is a "window" of 25 lines. By pressing the "f" key you will load the first 25 lines of the message. Each subsequent press of the "f" key will move the lines up one row and then display the newest line on the bottom. If you uncomment one line in the code (marked in the code as to which line) then it will only print 1 line at a time with each press of the "f" key until it gets to the 25th line then it will start at the top and work its way down moving the lines up 1 at a time.
What I'm having a problem understanding is how do I go backward i.e. scroll down until I get to the beginning of the buffer?
Also- is there an easier way to do what I have done here? I feel as though I made this harder than it needs to be but it has helped me learn this so far...
Appreciate any and all help / comments.
CON _clkmode = xtal1 + pll16x 'Standard clock mode * crystal frequency = 80 MHz _clkfreq = 80_000_000 MS_001 = 80_000_000 / 1_000 VAR byte message[4096] ' The actual message itself word messbeg[50] ' Character index number for the beginning of each message word messend[50] ' Character index number for the end of each message OBJ term : "FullDuplexSerial256" PUB Main | b, e, idx, i, line, r term.start(31, 30, %0000, 115_200) ' start terminal (use PST) pause(1000) line := 1 ' Line counter i := 0 b := 0 ' Message beginning index e := 0 ' Message end index term.str(string("Data String Size: ")) ' Report number of characters in data message in dat section term.dec(strsize(@data)) term.tx(13) term.str(string("Writing Data to Message buffer.... ")) repeat idx from 0 to 4095 ' Copy data message from dat section to message buffer message[idx] := byte[@data][idx] case message[idx] ' Test characters in data message... 00: ' If "00" it indicates end of message string. Stop saving to buffer quit 02: ' If "02" STX then store character number (index) to messbeg buffer messbeg[b++] := idx 03: ' If "03" ETX then store character number (index) to messend buffer messend[e++] := idx term.dec(idx) ' Indicate how many characters transferred. Should be same as data string size above. term.str(string(" Characters. Done",13)) i := 0 ' Initialize i term.tx(14) ' Set cursor to Home term.tx(0) term.tx(15) term.tx(0) repeat r := term.rxcheck if r > -1 case r "f": ' Forward repeat idx from messbeg[i] to 4095 ' Repeat characters indexed by the beginning message pointer in messbeg term.tx(byte[@message][idx]) case byte[@message][idx] ' Test byte looking for STX, ETX or end of message 00: ' End of data message string term.tx(11) ' Clear to end of line term.str(string("End of data",13)) quit 02: ' Begining of message STX term.tx(11) ' Clear to end of line 03: ' End of message ETX line++ i++ 'quit ' Uncomment this to do 1 line at a time with each press of "f" case line 26: term.tx(14) ' Set cursor to Home term.tx(0) term.tx(15) term.tx(0) i := i - 24 ' Start top row at next line as indicated in messbeg buffer line := 1 ' Reset line index quit pub pause(ms) | t t := cnt repeat ms waitcnt(t += MS_001) DAT data byte 02,"Command: Setup 31H Validator Response: Up to 27 Bytes Z0 - Z26",10,10,13,03 byte 02,"Z0 = Bill Validator Feature (MDB) Level - 1 byte",10,13,03 byte 02," Indicates current feature level of the bill validator. Currently defined",10,13,03 byte 02," levels are:",10,13,03 byte 02," Level 1 - does not support option bits. (Z1 = 01H)",10,13,03 byte 02," Level 2 - supports option bits. (Z1 = 02H)",10,10,13,03 byte 02,"Z1 - Z2 = Country / Currency code - 2 bytes",10,13,03 byte 02," The packed BCD country / currency code of the bill validator can be",10,13,03 byte 02," sent in 2 different forms depending on the valuse of the left most",10,13,03 byte 02," BCD digit.",10,13,03 byte 02," If the left most digit is a 0, the International Telephone Code is used",10,13,03 byte 02," to indicate the country that the validator is set-up for. For example,",10,13,03 byte 02," the USA code is 00 01H (Z1 = 00, Z2 = 01).",10,13,03 byte 02," If the left most digit is a 1, the latest version of the ISO 4217 numneric",10,13,03 byte 02," currency code is used. For example, the code for the US dollar is 18 40H",10,13,03 byte 02," (Z1 = 18, Z2 = 40). All new designs after 2000 must use ISO 4217.",10,10,13,03 byte 02,"Z3 - Z4 = Bill Scaling Factor - 2 bytes",10,13,03 byte 02," All accepted bill values must be evenly divisble by this number. For USA",10,13,03 byte 02," it would be 00 64H (0100 decimal).",10,10,13,03 byte 02,"Z5 = Decimal Places - 1 byte",10,13,03 byte 02," Indicates the number of decimal places on the credit display.",10,10,13,03 byte 02,"Z6 - Z7 = Stacker Capacity - 2 bytes",10,13,03 byte 02," Indicates the number of bills the stacker will hold.",10,10,13,03 byte 02,"Z8 - Z9 = Bill Security Levels - 2 bytes",10,13,03 byte 02," Indicates the security level for bill types 0 to 15. Since not all",10,13,03 byte 02," validators support multiple security levels, validators that do not have",10,13,03 byte 02," this feature must report a 'high' security level.",10,10,13,03 byte 02,"Z10 = Escrow / No Escrow - 1 byte",10,13,03 byte 02," Indicates the escrow capability of the bill validator. If Z10 = 00H, the",10,13,03 byte 02," bill validator does not have escrow capability. If Z10 = FFH, the bill",10,13,03 byte 02," validator has escrow capability.",10,10,13,03 byte 02,"Z11-Z26 = Bill Type Credit - 16 bytes",10,13,03 byte 02," Indicates the value of the bill types 0 to 15. Values must be sent in",10,13,03 byte 02," ascending order. This number is the bill's monetary value divided by",10,13,03 byte 02," the bill scaling factor. Unused bill types are sent as 00H. Unsent bill",10,13,03 byte 02," types are assumed to be zero. FFH bills are assumed to be vend tokens.",10,13,03,0The way I would do it is to have a method that just displays 25 lines (or less if the end is hit) starting at a specific index. Then when f or p is pressed increment or decrement the index and call the display method. However that would require rewriting chunks of the above. I came up with an easier to implement solution using your existing code. I just copied the block for the "f" keypress and added a "p" keypress section the only difference between that and the "f" section is that the index is decremented by 2 first. That seemed to do what you want.
CON _clkmode = xtal1 + pll16x 'Standard clock mode * crystal frequency = 80 MHz _clkfreq = 80_000_000 MS_001 = 80_000_000 / 1_000 VAR byte message[4096] ' The actual message itself word messbeg[50] ' Character index number for the beginning of each message word messend[50] ' Character index number for the end of each message OBJ term : "FullDuplexSerial256" PUB Main | b, e, idx, i, line, r term.start(31, 30, 00, 115_200) ' start terminal (use PST) pause(1000) line := 1 ' Line counter i := 0 b := 0 ' Message beginning index e := 0 ' Message end index term.str(string("Data String Size: ")) ' Report number of characters in data message in dat section term.dec(strsize(@data)) term.tx(13) term.str(string("Writing Data to Message buffer.... ")) repeat idx from 0 to 4095 ' Copy data message from dat section to message buffer message[idx] := byte[@data][idx] case message[idx] ' Test characters in data message... 00: ' If "00" it indicates end of message string. Stop saving to buffer quit 02: ' If "02" STX then store character number (index) to messbeg buffer messbeg[b++] := idx 03: ' If "03" ETX then store character number (index) to messend buffer messend[e++] := idx term.dec(idx) ' Indicate how many characters transferred. Should be same as data string size above. term.str(string(" Characters. Done",13)) i := 0 ' Initialize i term.tx(14) ' Set cursor to Home term.tx(0) term.tx(15) term.tx(0) repeat r := term.rxcheck if r > -1 case r "f": ' Forward repeat idx from messbeg[i] to 4095 ' Repeat characters indexed by the beginning message pointer in messbeg term.tx(byte[@message][idx]) case byte[@message][idx] ' Test byte looking for STX, ETX or end of message 00: ' End of data message string term.tx(11) ' Clear to end of line term.str(string("End of data",13)) quit 02: ' Begining of message STX term.tx(11) ' Clear to end of line 03: ' End of message ETX line++ i++ 'quit ' Uncomment this to do 1 line at a time with each press of "f" case line 26: term.tx(14) ' Set cursor to Home term.tx(0) term.tx(15) term.tx(0) i := i - 24 ' Start top row at next line as indicated in messbeg buffer line := 1 ' Reset line index quit "p": if i>1 i-=2 else i:=0 ' back to previous line repeat idx from messbeg[i] to 4095 ' Repeat characters indexed by the beginning message pointer in messbeg term.tx(byte[@message][idx]) case byte[@message][idx] ' Test byte looking for STX, ETX or end of message 00: ' End of data message string term.tx(11) ' Clear to end of line term.str(string("End of data",13)) quit 02: ' Begining of message STX term.tx(11) ' Clear to end of line 03: ' End of message ETX line++ i++ 'quit ' Uncomment this to do 1 line at a time with each press of "f" case line 26: term.tx(14) ' Set cursor to Home term.tx(0) term.tx(15) term.tx(0) i := i - 24 ' Start top row at next line as indicated in messbeg buffer line := 1 ' Reset line index quit pub pause(ms) | t t := cnt repeat ms waitcnt(t += MS_001) DAT data byte 02,"Command: Setup 31H Validator Response: Up to 27 Bytes Z0 - Z26",10,10,13,03 byte 02,"Z0 = Bill Validator Feature (MDB) Level - 1 byte",10,13,03 byte 02," Indicates current feature level of the bill validator. Currently defined",10,13,03 byte 02," levels are:",10,13,03 byte 02," Level 1 - does not support option bits. (Z1 = 01H)",10,13,03 byte 02," Level 2 - supports option bits. (Z1 = 02H)",10,10,13,03 byte 02,"Z1 - Z2 = Country / Currency code - 2 bytes",10,13,03 byte 02," The packed BCD country / currency code of the bill validator can be",10,13,03 byte 02," sent in 2 different forms depending on the valuse of the left most",10,13,03 byte 02," BCD digit.",10,13,03 byte 02," If the left most digit is a 0, the International Telephone Code is used",10,13,03 byte 02," to indicate the country that the validator is set-up for. For example,",10,13,03 byte 02," the USA code is 00 01H (Z1 = 00, Z2 = 01).",10,13,03 byte 02," If the left most digit is a 1, the latest version of the ISO 4217 numneric",10,13,03 byte 02," currency code is used. For example, the code for the US dollar is 18 40H",10,13,03 byte 02," (Z1 = 18, Z2 = 40). All new designs after 2000 must use ISO 4217.",10,10,13,03 byte 02,"Z3 - Z4 = Bill Scaling Factor - 2 bytes",10,13,03 byte 02," All accepted bill values must be evenly divisble by this number. For USA",10,13,03 byte 02," it would be 00 64H (0100 decimal).",10,10,13,03 byte 02,"Z5 = Decimal Places - 1 byte",10,13,03 byte 02," Indicates the number of decimal places on the credit display.",10,10,13,03 byte 02,"Z6 - Z7 = Stacker Capacity - 2 bytes",10,13,03 byte 02," Indicates the number of bills the stacker will hold.",10,10,13,03 byte 02,"Z8 - Z9 = Bill Security Levels - 2 bytes",10,13,03 byte 02," Indicates the security level for bill types 0 to 15. Since not all",10,13,03 byte 02," validators support multiple security levels, validators that do not have",10,13,03 byte 02," this feature must report a 'high' security level.",10,10,13,03 byte 02,"Z10 = Escrow / No Escrow - 1 byte",10,13,03 byte 02," Indicates the escrow capability of the bill validator. If Z10 = 00H, the",10,13,03 byte 02," bill validator does not have escrow capability. If Z10 = FFH, the bill",10,13,03 byte 02," validator has escrow capability.",10,10,13,03 byte 02,"Z11-Z26 = Bill Type Credit - 16 bytes",10,13,03 byte 02," Indicates the value of the bill types 0 to 15. Values must be sent in",10,13,03 byte 02," ascending order. This number is the bill's monetary value divided by",10,13,03 byte 02," the bill scaling factor. Unused bill types are sent as 00H. Unsent bill",10,13,03 byte 02," types are assumed to be zero. FFH bills are assumed to be vend tokens.",10,13,03,0Start your 2048 character buffer with ETX as the first character and have each message terminated with an ETX.
Have a single method that scans up or down depending on the parameter it is called with.
Something like: " scan(curr_pos, 1)" to scan forward and "scan(curr_pos, -1) to go backwards.