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tablekt

Provides k-rate control over table numbers.

The standard Csound opcode table when producing a k- or a-rate result, can only use an init-time variable to select the table number. tablekt accepts k-rate control as well as i-time. In all other respects they are similar to the original opcodes.

Syntax

ares tablekt xndx, kfn [, ixmode] [, ixoff] [, iwrap]
kres tablekt kndx, kfn [, ixmode] [, ixoff] [, iwrap]

Initialization

ixmode -- if 0, xndx and ixoff ranges match the length of the table. if non-zero xndx and ixoff have a 0 to 1 range. Default is 0

ixoff -- if 0, total index is controlled directly by xndx, ie. the indexing starts from the start of the table. If non-zero, start indexing from somewhere else in the table. Value must be positive and less than the table length (ixmode = 0) or less than 1 (ixmode not equal to 0). Default is 0.

iwrap -- if iwrap = 0, Limit mode: when total index is below 0, then final index is 0.Total index above table length results in a final index of the table length - high out of range total indexes stick at the upper limit of the table. If iwrap not equal to 0, Wrap mode: total index is wrapped modulo the table length so that all total indexes map into the table. For instance, in a table of length 8, xndx = 5 and ixoff = 6 gives a total index of 11, which wraps to a final index of 3. Default is 0.

Performance

kndx -- Index into table, either a positive number range matching the table length (ixmode = 0) or a 0 to 1 range (ixmode not equal to 0).

xndx -- matching the table length (ixmode = 0) or a 0 to 1 range (ixmode not equal to 0)

kfn -- Table number. Must be >= 1. Floats are rounded down to an integer. If a table number does not point to a valid table, or the table has not yet been loaded (GEN01) then an error will result and the instrument will be de-activated.

⚠ Caution with k-rate table numbers

At k-rate, if a table number of < 1 is given, or the table number points to a non-existent table, or to one which has a length of 0 (it is to be loaded from a file later) then an error will result and the instrument will be deactivated. kfn must be initialized at the appropriate rate using init. Attempting to load an i-rate value into kfn will result in an error.

Examples

Here is an example of the tablekt opcode. It uses the file tablekt.csd.

Example of the tablekt opcode.
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<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
-odac     ;;;realtime audio out
;-iadc    ;;;uncomment -iadc if RT audio input is needed too
; For Non-realtime ouput leave only the line below:
; -o tablekt.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

sr = 44100
ksmps = 32
nchnls = 2
0dbfs  = 1

seed 0

gift1 ftgen 1, 0, 1024, 10, 1                           ;sine wave
gift2 ftgen 2, 0, 1024, 10, 1, 1, 1, 1, 1, 1, 1, 1, 1   ;pulse


instr 1
andx phasor 400                 ;phasor for reading the index
kfn init 1                      ;initialize the choice of the function table
kmetro init 1                   ;initialize the frequency of the metro
knewft metro kmetro             ;make a new choice for selecting the function table once a second

if knewft == 1 then
  kfn = (kfn == 1 ? 2 : 1)      ;switch between 1 and 2
  kmetro random .5, 2           ;create new metro frequency
  printk2 kfn
endif

ares tablekt andx, kfn, 1
outs ares,  ares
endin

</CsInstruments>
<CsScore>
i 1 0 10
e
</CsScore>
</CsoundSynthesizer>

Its output should include lines like these:

i1     2.00000
i1     1.00000
i1     2.00000
i1     1.00000
....

See also

Table Reading with Dynamic Selection

Credits

Author: Robin Whittle
Australia
May 1997

New in version 3.47