Function u4_add_internal_stack

bitvm/src/u4/u4_add_stack.rs:90–123

Addition of numbers consisting of nibble_count u4's in the parameter bases locations The overflowing bit (if exists) is omitted

(
    stack: &mut StackTracker,
    nibble_count: u32,
    number_count: u32,
    quotient_table: StackVariable,
    modulo_table: StackVariable,
)

/// Addition of numbers consisting of nibble_count u4's in the parameter bases locations
/// The overflowing bit (if exists) is omitted
pub fn u4_add_internal_stack(
    stack: &mut StackTracker,
    nibble_count: u32,
    number_count: u32,
    quotient_table: StackVariable,
    modulo_table: StackVariable,
) {
    for i in 0..nibble_count {
        //extra add to add the carry from previous addition
        if i > 0 {
            stack.op_add();
        }

        //add the column of nibbles (needs one less add than nibble count)
        for _ in 0..number_count - 1 {
            stack.op_add();
        }

        // duplicate the result to be used to get the carry except for the last nibble
        if i < nibble_count - 1 {
            stack.op_dup();
        }

        //get the modulo of the addition
        stack.get_value_from_table(modulo_table, None);
        stack.to_altstack();

        //we don't care about the last carry
        if i < nibble_count - 1 {
            //obtain the quotinent to be used as carry for the next addition
            stack.get_value_from_table(quotient_table, None);
        }
    }
}

#[cfg(test)]
mod tests {