testlist <- list(a = c(1186299162L, -999321685L, -372369382L, 976749074L,  1611714470L, 793377221L, 334149736L, 1555980450L, 1943911479L,  1280041525L, 435834707L, 844195219L, 1630878096L, 2117228177L,  487520889L, -866510017L, 936867460L, 576239931L, 1376358021L,  1525946556L, 693193895L, -2069743199L, -1322050947L, -1925857852L,  204687406L, -1945998882L, 200762213L, -344252140L, -848380847L,  284553921L, 671891381L, 1107065165L, NA, -991651121L, -604162873L,  2035735366L, -996698156L, -1937140044L, -1781175850L, -773643520L,  -1516323735L, -2108278691L, 1399596236L, -1040182650L, -1750508764L,  854710471L, -968712809L, 633378762L, 1582511072L, -1452589315L,  -681391718L, 1658593530L, -2055528776L, 1828093746L, 941476189L,  -580835524L, -1269162914L, -983934051L, -1121700065L, 5708166L,  -751354305L, 784167526L, -633617224L, -1662258095L, 1175498507L,  1795860520L, 786384687L, 929150218L, -1728886330L, -1329910389L,  -135183469L, -600316894L, 1200828082L, -1646863668L, -1239221267L,  1433470455L, -1556028845L, -66068749L, 2197212L, 1483472800L,  -30584164L, 53307577L, 1331930834L, 329117110L, -556856870L,  -555168290L, 156482402L), b = c(-563274520L, NA, NA, -1600822494L,  1443361402L))
result <- do.call(padr:::round_up_core_prev,testlist)
str(result)