Tests for the `downto` variant too.
Chris Pressey
3 years ago
| 1708 | 1708 | | } |
| 1709 | 1709 | ? RangeExceededError |
| 1710 | 1710 | |
| 1711 | In a "for" loop (downto variant), we know the exact range the loop variable takes on. | |
| 1712 | ||
| 1713 | | byte table[16] tab | |
| 1714 | | | |
| 1715 | | define foo routine inputs tab trashes a, x, c, z, v, n { | |
| 1716 | | ld x, 15 | |
| 1717 | | for x downto 0 { | |
| 1718 | | ld a, tab + x | |
| 1719 | | } | |
| 1720 | | } | |
| 1721 | = ok | |
| 1722 | ||
| 1723 | | byte table[15] tab | |
| 1724 | | | |
| 1725 | | define foo routine inputs tab trashes a, x, c, z, v, n { | |
| 1726 | | ld x, 15 | |
| 1727 | | for x downto 0 { | |
| 1728 | | ld a, tab + x | |
| 1729 | | } | |
| 1730 | | } | |
| 1731 | ? RangeExceededError | |
| 1732 | ||
| 1733 | You cannot modify the loop variable in a "for" loop (downto variant). | |
| 1734 | ||
| 1735 | | byte table[16] tab | |
| 1736 | | | |
| 1737 | | define foo routine inputs tab trashes a, x, c, z, v, n { | |
| 1738 | | ld x, 15 | |
| 1739 | | for x downto 0 { | |
| 1740 | | ld x, 0 | |
| 1741 | | } | |
| 1742 | | } | |
| 1743 | ? ForbiddenWriteError | |
| 1744 | ||
| 1745 | If the range isn't known to be larger than the final value, you can't go down to it. | |
| 1746 | ||
| 1747 | | byte table[32] tab | |
| 1748 | | | |
| 1749 | | define foo routine inputs tab trashes a, x, c, z, v, n { | |
| 1750 | | ld x, 0 | |
| 1751 | | for x downto 0 { | |
| 1752 | | ld a, tab + x | |
| 1753 | | } | |
| 1754 | | } | |
| 1755 | ? RangeExceededError | |
| 1756 | ||
| 1711 | 1757 | ### copy ### |
| 1712 | 1758 | |
| 1713 | 1759 | Can't `copy` from a memory location that isn't initialized. |