tiny.accy.kernel.library.extent

1const std = @import("std");23pub const runtime_extent_max: u64 = @as(u64, @intCast(std.math.maxInt(i32)));45pub fn indexExtent(extent: u64) !i64 {6    return std.math.cast(i64, extent) orelse error.ExtentOverflowsIndexRange;7}89pub fn indexProduct(lhs: u64, rhs: u64) !i64 {10    const product = std.math.mul(u64, lhs, rhs) catch return error.ExtentOverflowsIndexRange;11    return indexExtent(product);12}1314pub fn runtimeExtentArgument(extent: u64) !u32 {15    if (extent == 0 or extent > runtime_extent_max) return error.ExtentOverflowsIndexRange;16    return @intCast(extent);17}1819pub fn blockCountWithinLimit(extent: u64, threads: u32, max_blocks: u32) bool {20    if (threads == 0) return false;21    return extent <= @as(u64, threads) * max_blocks;22}2324const testing = std.testing;2526test "index extent accepts the full unsigned index range" {27    try testing.expectEqual(@as(i64, 0), try indexExtent(0));28    try testing.expectEqual(@as(i64, std.math.maxInt(i64)), try indexExtent(@as(u64, @intCast(std.math.maxInt(i64)))));29    try testing.expectError(error.ExtentOverflowsIndexRange, indexExtent(@as(u64, @intCast(std.math.maxInt(i64))) + 1));30}3132test "index product checks overflow before conversion" {33    try testing.expectEqual(@as(i64, 12), try indexProduct(3, 4));34    try testing.expectError(error.ExtentOverflowsIndexRange, indexProduct(std.math.maxInt(u64), 2));35}3637test "runtime extent argument bounds to nonzero i32 range" {38    try testing.expectEqual(@as(u32, 1), try runtimeExtentArgument(1));39    try testing.expectEqual(@as(u32, @intCast(runtime_extent_max)), try runtimeExtentArgument(runtime_extent_max));40    try testing.expectError(error.ExtentOverflowsIndexRange, runtimeExtentArgument(0));41    try testing.expectError(error.ExtentOverflowsIndexRange, runtimeExtentArgument(runtime_extent_max + 1));42}4344test "block count limit rejects oversized extents without overflowing" {45    try testing.expect(blockCountWithinLimit(1, 32, 4));46    try testing.expect(blockCountWithinLimit(128, 32, 4));47    try testing.expect(!blockCountWithinLimit(129, 32, 4));48    try testing.expect(!blockCountWithinLimit(std.math.maxInt(u64), 32, 1024));49    try testing.expect(!blockCountWithinLimit(1, 0, 1024));50}

1pub const extent = @import("extent.zig");