More tests for "for" loops.
Chris Pressey
3 years ago
| 1807 | 1807 | | } |
| 1808 | 1808 | ? UnmeaningfulReadError |
| 1809 | 1809 | |
| 1810 | Because routines current do not express range constraints, It may not do to take the loop variable as an input. (?) | |
| 1810 | Because routines currently do not include range constraints, | |
| 1811 | the loop variable may not be useful as an input (the location | |
| 1812 | is assumed to have the maximum range.) | |
| 1811 | 1813 | |
| 1812 | 1814 | | byte table[16] tab |
| 1813 | 1815 | | |
| 1924 | 1926 | | } |
| 1925 | 1927 | ? UnmeaningfulReadError: y |
| 1926 | 1928 | |
| 1929 | The "for" loop does not preserve the `z` or `n` registers. | |
| 1930 | ||
| 1931 | | define foo routine trashes x { | |
| 1932 | | ld x, 0 | |
| 1933 | | for x up to 15 { | |
| 1934 | | } | |
| 1935 | | } | |
| 1936 | ? ForbiddenWriteError | |
| 1937 | ||
| 1938 | But it does preserve the other registers, such as `c`. | |
| 1939 | ||
| 1940 | | define foo routine trashes x, z, n { | |
| 1941 | | ld x, 0 | |
| 1942 | | for x up to 15 { | |
| 1943 | | } | |
| 1944 | | } | |
| 1945 | = ok | |
| 1946 | ||
| 1947 | In fact it does not strictly trash `z` and `n`, as they are | |
| 1948 | always set to known values after the loop. TODO: document | |
| 1949 | what these known values are! | |
| 1950 | ||
| 1951 | | define foo routine outputs z, n trashes x { | |
| 1952 | | ld x, 0 | |
| 1953 | | for x up to 15 { | |
| 1954 | | } | |
| 1955 | | } | |
| 1956 | = ok | |
| 1957 | ||
| 1927 | 1958 | #### downward-counting variant |
| 1928 | 1959 | |
| 1929 | 1960 | In a "for" loop (downward-counting variant), we know the exact range the loop variable takes on. |
| 1982 | 2013 | | } |
| 1983 | 2014 | | } |
| 1984 | 2015 | ? RangeExceededError |
| 2016 | ||
| 2017 | The "for" loop does not preserve the `z` or `n` registers. | |
| 2018 | ||
| 2019 | | define foo routine trashes x { | |
| 2020 | | ld x, 15 | |
| 2021 | | for x down to 0 { | |
| 2022 | | } | |
| 2023 | | } | |
| 2024 | ? ForbiddenWriteError | |
| 2025 | ||
| 2026 | But it does preserve the other registers, such as `c`. | |
| 2027 | ||
| 2028 | | define foo routine trashes x, z, n { | |
| 2029 | | ld x, 15 | |
| 2030 | | for x down to 0 { | |
| 2031 | | } | |
| 2032 | | } | |
| 2033 | = ok | |
| 2034 | ||
| 2035 | In fact it does not strictly trash `z` and `n`, as they are | |
| 2036 | always set to known values after the loop. TODO: document | |
| 2037 | what these known values are! | |
| 2038 | ||
| 2039 | | define foo routine outputs z, n trashes x { | |
| 2040 | | ld x, 15 | |
| 2041 | | for x down to 0 { | |
| 2042 | | } | |
| 2043 | | } | |
| 2044 | = ok | |
| 1985 | 2045 | |
| 1986 | 2046 | ### save ### |
| 1987 | 2047 | |