Description
Return zero guardBits for one summand, otherwise ceil(log2(summandCount)).
Adding bounded fixed-point values can require more accumulator bits than storing one operand. A count-based guard allowance addresses worst-case growth rather than actual signal statistics.
Return zero guardBits for one summand, otherwise ceil(log2(summandCount)).
When to use this tool
Use Microcontroller: Fixed Point Accumulator Guard Bit Count when you need a summation guard-bit budget.
How to use the tool and how it works
- Enter summandCount. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read result. Expand result to inspect the returned fields.
Return zero guardBits for one summand, otherwise ceil(log2(summandCount)).1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| summandCount | Summand Count | Required. Safe integer. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| result | Result | Required. Object. |
| result.guardBits | Additional accumulator bits under the stated count-growth model. | Calculated result member: number. |
{
"input": {
"summandCount": 5
},
"output": {
"result": {
"guardBits": 3
}
}
}Limitations and assumptions
- This is a count-based worst-case growth allowance; signedness, operand widths, scaling, saturation, and actual bounds need separate analysis.
- Outputs are nested inside result. Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Derive bounds from operand ranges and scaling, then verify accumulator signedness and overflow behavior.
References
Similar or alternative tools
- ADC Oversampling Bit Gain Budget
Return 4^additionalBits samples and shiftBits equal to additionalBits for an integer gain request from zero through 20.
- SPI Word Padding Bit Count
Round dataBits up to a whole number of wordBits-sized words and return the unused trailing bit count.