// SPDX-License-Identifier: Apache-2.0
; specs/widgets/golden-gf256.t27 -- the infographic of lesson 21 of the GoldenFloat course (specs/course/goldenfloat.t27)
; Source of truth for public/widgets/golden-gf256/ (gHashTag/trinity): scripts/widget-pages-from-spec.mjs compiles
; this file, checks its constants, evaluates the tests below and writes the page. tool.js is one import of
; ../infographic.js, which draws SAY_TABLE_* as a real <table> and SAY_FLOW_* as an SVG diagram with a
; <title>, black and white, and holds no words of its own. ASCII only (L3), English only (LANG-EN).
; The lesson spec it illustrates: public/t27/files/specs/numeric/gf256.t27.
; phi^2 + 1/phi^2 = 3 | TRINITY

module widget_golden_gf256;

pub const KIND : str = "widget-tool";
pub const ID : str = "golden-gf256";
pub const TITLE : str = "GoldenFloat 21: GF256";
pub const DESCRIPTION : str = "GF256: 256 bits as the spec lays them out, read from gf256.t27. Lesson 21 of the GoldenFloat course.";
pub const IMAGE_ALT : str = "A black and white table, GF256: 256 bits as the spec lays them out: Sign, 1 bit, SIGN_BITS; Exponent, 97 bits, EXP_BITS; Mantissa, 158 bits, MANT_BITS; Bias, 2^(97-1) - 1, BIAS = 2^(E-1) - 1; Top exponent code, 2^97 - 1, EXP_MAX = 2^E - 1.";
pub const HOOK : str = "256 bits split by phi: 1 sign, 97 exponent, 158 mantissa.";
pub const CATEGORY : str = "compiler";
pub const DATA_SOURCES : [2]str = ["The lesson spec public/t27/files/specs/numeric/gf256.t27, read when the course was authored; every number in the table is a constant, a test value or arithmetic of that file", "Nothing on this page was measured on hardware or timed; a value written into a test is said to be written in, not computed"];
pub const READS_LOCAL_FILES : bool = false;
pub const SENDS_NOTHING : bool = true;

; --- The table -----------------------------------------------------------------------------
pub const SAY_TABLE_CAPTION : str = "GF256: 256 bits as the spec lays them out";
pub const SAY_TABLE_HEAD : [3]str = ["Field", "Value", "Spec constant"];
pub const SAY_TABLE_CELLS : [15]str = ["Sign", "1 bit", "SIGN_BITS", "Exponent", "97 bits", "EXP_BITS", "Mantissa", "158 bits", "MANT_BITS", "Bias", "2^(97-1) - 1", "BIAS = 2^(E-1) - 1", "Top exponent code", "2^97 - 1", "EXP_MAX = 2^E - 1"];
pub const K_TABLE_COLS : u8 = 3;
pub const K_TABLE_ROWS : u8 = 5;
pub const K_TABLE_CELLS : u16 = 15;

; --- The diagram and the note ----------------------------------------------------------------
pub const SAY_FLOW_TITLE : str = "How GF256 gets its split";
pub const SAY_FLOW_STEPS : [3]str = ["N = 256 bits", "E = round((256 - 1) / phi^2) = 97", "M = 256 - 1 - 97 = 158"];
pub const K_FLOW_STEPS : u8 = 3;
pub const SAY_NOTE : str = "Every number above is a constant of gf256.t27; its tests check 1 + 97 + 158 = 256.";

test the_cells_fill_whole_rows {
    assert K_TABLE_ROWS * K_TABLE_COLS == K_TABLE_CELLS;
}

test the_table_has_a_body {
    assert K_TABLE_ROWS > 0;
    assert K_TABLE_COLS > 0;
}

test the_diagram_has_every_step {
    assert K_FLOW_STEPS == 3;
    assert K_FLOW_STEPS > 1;
}