Code 1 is never used when reporting a distribution from a Roth IRA. Code 1 with the IRA/SEP/SIMPLE box marked indicates an early distribution from a traditional IRA, not a distribution from a Roth IRA.
The entire distribution from a traditional IRA is taxable unless you have basis in nondeductible traditional IRA contributions. Perhaps you actually made nondeductible contributions to a traditional IRA, not contributions to a Roth IRA, in which case your tax return would need to include Form 8606 Part I on which the taxable amount of the distribution would be calculated.
