term: 7-color terminal (per-glyph fg+bg) + ANSI escapes; colorize irc

Fano-plane palette scheme: the 7 colors map onto 7 CGB BG palettes so
any color pair shares one palette; a tile's palette is picked from the
set of colors its two cells need (tables generated by tools/gencolor.py).
Per cell a packed (bg<<4)|fg byte lives alongside the char shadow, and
the glyph blitter steers glyph/empty pixels to each cell's fg/bg color
slots via plane masks.

An ANSI-ish CSI parser (ESC [ .. m) drives it; usr/ansi.c demos it and
the irc client now renders hashed nick colors, status dimming and a
channel-activity bar.

4 files changed, 549 insertions, 29 deletions

diff --git a/src/color.asm b/src/color.asm
new file mode 100644
index 0000000..5c12569
--- /dev/null
+++ b/src/color.asm
@@ -0,0 +1,40 @@
+; auto-generated by tools/gencolor.py - Fano-plane color tables
+; (foreground + background). DO NOT EDIT.
+SECTION "color", ROM0
+
+; 8 CGB BG palettes, 4 colors each (c0=black). Loaded at BCPS $80.
+PalData::
+    db $00,$00,$FF,$7F,$1F,$00,$E0,$7F    ; palette 0
+    db $FF,$7F,$00,$00,$00,$00,$00,$00    ; palette 1
+    db $00,$00,$1F,$00,$E0,$03,$FF,$03    ; palette 2
+    db $00,$00,$1F,$00,$00,$7C,$1F,$7C    ; palette 3
+    db $00,$00,$E0,$03,$00,$7C,$E0,$7F    ; palette 4
+    db $00,$00,$E0,$03,$1F,$7C,$FF,$7F    ; palette 5
+    db $00,$00,$FF,$03,$00,$7C,$FF,$7F    ; palette 6
+    db $00,$00,$FF,$03,$1F,$7C,$E0,$7F    ; palette 7
+
+; BitTab[color] = bit for that color in the 'colors present' set (black=0)
+BitTab::
+    db $00,$01,$02,$04,$08,$10,$20,$40
+
+; BestPal[set] = palette (0..7) covering the most colors in a 7-bit set
+BestPal::
+    db $00,$00,$02,$02,$02,$02,$02,$02,$03,$03,$04,$02,$06,$02,$02,$02  ; 0..15
+    db $03,$03,$05,$02,$07,$02,$02,$02,$03,$03,$03,$03,$03,$03,$02,$02  ; 16..31
+    db $00,$00,$04,$00,$07,$00,$02,$02,$04,$00,$04,$04,$04,$00,$04,$02  ; 32..47
+    db $07,$00,$04,$00,$07,$07,$07,$02,$03,$03,$04,$03,$07,$03,$04,$02  ; 48..63
+    db $00,$00,$05,$00,$06,$00,$02,$02,$06,$00,$04,$00,$06,$06,$06,$02  ; 64..79
+    db $05,$00,$05,$05,$05,$00,$05,$02,$03,$03,$05,$03,$06,$03,$05,$02  ; 80..95
+    db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$04,$00,$06,$00,$04,$00  ; 96..111
+    db $00,$00,$05,$00,$07,$00,$05,$00,$00,$00,$04,$00,$06,$00,$04,$00  ; 112..127
+
+; SlotOf[palette*8 + color] = that color's slot/id (0..3) in the palette
+SlotOf::
+    db $00,$02,$01,$01,$01,$01,$03,$01  ; palette 0
+    db $00,$01,$01,$01,$01,$01,$01,$01  ; palette 1
+    db $00,$01,$02,$03,$01,$01,$01,$01  ; palette 2
+    db $00,$01,$01,$01,$02,$03,$01,$01  ; palette 3
+    db $00,$01,$01,$01,$02,$01,$03,$01  ; palette 4
+    db $00,$01,$01,$01,$01,$02,$01,$03  ; palette 5
+    db $00,$01,$01,$01,$02,$01,$01,$03  ; palette 6
+    db $00,$01,$01,$01,$01,$02,$03,$01  ; palette 7
diff --git a/src/osk.asm b/src/osk.asm
index f5d99ac..d5edad7 100644
--- a/src/osk.asm
+++ b/src/osk.asm
@@ -80,10 +80,16 @@ osk_init::
     ld [rBCPD], a
     ld [rBCPD], a               ; c1 = $0000 black
 
-    ; build the key tiles (no cursor underline)
+    ; build the key tiles (no cursor underline). Glyph pixels -> color-id 1
+    ; (palette slot 1: white normal / black inverted); empty pixels -> id 0.
     xor a
     ld [wCurMask], a
     ld [wOskBuild], a
+    ld [wFGP1], a
+    ld [wBGP0], a
+    ld [wBGP1], a
+    ld a, $FF
+    ld [wFGP0], a
 .build
     ld a, [wOskBuild]
     ld e, a
diff --git a/src/programs.asm b/src/programs.asm
index 7c17fb5..c6228f3 100644
--- a/src/programs.asm
+++ b/src/programs.asm
@@ -136,6 +136,9 @@ ProgIrc:
 SECTION "prog_uptime", ROMX[$4000], BANK[33]
 ProgUptime:
     INCBIN "build/usr/uptime.bin"
+SECTION "prog_ansi",   ROMX[$4000], BANK[34]
+ProgAnsi:
+    INCBIN "build/usr/ansi.bin"
 
 ; -----------------------------------------------------------------------------
 ; PROG_SH (bank 3) - the shell, now written in C (usr/sh.c): parses >/</| and
@@ -242,6 +245,8 @@ ProgramTable::
     dw ProgIrc
     db LOW(BANK(ProgUptime)), HIGH(BANK(ProgUptime))
     dw ProgUptime
+    db LOW(BANK(ProgAnsi)), HIGH(BANK(ProgAnsi))
+    dw ProgAnsi
 ProgramTableEnd::
 
 ; -----------------------------------------------------------------------------
@@ -313,4 +318,6 @@ NameTable::
     db PROG_IRC
     db "uptime", 0
     db PROG_UPTIME
+    db "ansi", 0
+    db PROG_ANSI
     db 0
diff --git a/src/term.asm b/src/term.asm
index 099ca0a..d62310e 100644
--- a/src/term.asm
+++ b/src/term.asm
@@ -23,6 +23,8 @@ DEF TCOLS   EQU 40      ; text columns
 DEF TROWS   EQU 18      ; text rows
 DEF TSTRIDE EQU 64      ; bytes per line-slot in the buffer (power of 2)
 DEF TERM_BUF EQU $D600  ; 18*64 = 1152 B (WRAMX, above the FS caches)
+DEF COL_BUF  EQU $DA80  ; per-cell fg color, parallel to TERM_BUF (18*64 = 1152 B)
+DEF COL_OFF  EQU COL_BUF - TERM_BUF   ; $0480: add to a char addr -> its color addr
 
 ; terminal state (WRAMX gap $D580-$D5FF)
 DEF wGlyphL   EQU $D580  ; 2
@@ -53,24 +55,20 @@ term_init::
     ld [rSCX], a
     ld [rSCY], a
 
-    ; BG palette 0: color0 = black (bg), color1 = white (text) - dark terminal
-    ld a, $80
+    ; Load all 8 CGB BG palettes from PalData (see tools/gencolor.py). Palettes
+    ; 0 and 2..7 are the 7 Fano-plane text palettes (each = bg + 3 of our 7
+    ; colors); palette 1 is the OSK's white-on-black inverse. Per-glyph color
+    ; works because each tile picks the one palette that holds both its glyphs'
+    ; colors, and the two bitplanes steer each glyph to its color's slot.
+    ld a, $80                   ; BCPS index 0, auto-increment
     ld [rBCPS], a
-    xor a
-    ld [rBCPD], a
-    ld [rBCPD], a               ; c0 = $0000 black (background)
-    ld a, $FF
-    ld [rBCPD], a
-    ld a, $7F
-    ld [rBCPD], a               ; c1 = $7FFF white (text)
-    ld a, $FF
-    ld [rBCPD], a
-    ld a, $7F
-    ld [rBCPD], a               ; c2 = white
-    ld a, $FF
+    ld hl, PalData
+    ld b, 8 * 4 * 2             ; 8 palettes * 4 colors * 2 bytes
+.palcopy
+    ld a, [hl+]
     ld [rBCPD], a
-    ld a, $7F
-    ld [rBCPD], a               ; c3 = white
+    dec b
+    jr nz, .palcopy
 
     ; state: assign[sr]=sr, cursor at 0,0 (on)
     ld hl, wAssign
@@ -86,8 +84,11 @@ term_init::
     ld [wCurCol], a
     ld [wViewTop], a            ; view starts unshifted (all 18 rows)
     ld [wOskVisible], a         ; OSK hidden until toggled
+    ld [wAnsiState], a          ; ANSI parser idle
     ld a, 1
     ld [wCursorOn], a
+    ld a, 7
+    ld [wCurColor], a           ; default fg color = 7 (white)
 
     ; clear the buffer (all slots) to spaces
     ld hl, TERM_BUF
@@ -100,6 +101,17 @@ term_init::
     or e
     jr nz, .clr
 
+    ; clear the color buffer to the default fg color (7 = white)
+    ld hl, COL_BUF
+    ld de, TROWS * TSTRIDE
+.clrc
+    ld a, 7
+    ld [hl+], a
+    dec de
+    ld a, d
+    or e
+    jr nz, .clrc
+
     call term_write_tilemap
     call term_redraw            ; build all tiles (blank + cursor)
 
@@ -134,16 +146,47 @@ term_write_tilemap::
     ld [rVBK], a
     ld c, 0
 .a_row
-    call .slot20
+    call .slot20                ; DE = pos, HL = tilemap addr, wTMSlot = slot
     ld b, TCOLS/2
 .a_col
-    ld a, d                     ; HIGH(pos): 0 or 1
+    ; attribute = palette(from this tile's two cell colors) | bank bit(pos hi).
+    push hl                     ; save tilemap write ptr
+    push de                     ; save pos
+    ; color addr = COL_BUF + slot*64 + tcol*2 ; tcol = (TCOLS/2) - b
+    ld a, [wTMSlot]
+    ld l, a
+    ld h, 0
+    add hl, hl
+    add hl, hl
+    add hl, hl
+    add hl, hl
+    add hl, hl
+    add hl, hl                  ; slot*64
+    ld a, TCOLS/2
+    sub b
+    add a                       ; tcol*2
+    add l
+    ld l, a
+    ld a, h
+    adc 0
+    ld h, a
+    ld de, COL_BUF
+    add hl, de
+    ld a, [hl+]
+    ld d, a                     ; colL
+    ld a, [hl]
+    ld e, a                     ; colR
+    call color_setup            ; -> wPalAttr (preserves B, C)
+    pop de                      ; restore pos
+    pop hl                      ; restore tilemap write ptr
+    ld a, d                     ; HIGH(pos): 0 or 1 -> VRAM bank bit
     or a
     jr z, .a0
-    ld a, $08                   ; VRAM bank 1 attribute
+    ld a, [wPalAttr]
+    or $08                      ; VRAM bank 1 tile
     jr .aw
 .a0
-    xor a
+    ld a, [wPalAttr]
 .aw
     ld [hl+], a
     inc de
@@ -170,6 +213,7 @@ term_write_tilemap::
     adc 0
     ld h, a
     ld a, [hl]                  ; L = assign[logical row]
+    ld [wTMSlot], a             ; stash slot for the color-aware attr pass
     ld l, a
     ld h, 0
     add hl, hl
@@ -239,6 +283,135 @@ glyph_ptr:
     ret
 
 ; -----------------------------------------------------------------------------
+; color_setup - D = left cell packed color, E = right cell packed color (each
+; (bg<<4)|fg, 0..7 per nibble). Picks the tile's palette (wPalAttr) and the four
+; bitplane masks: wFGP0/wFGP1 steer GLYPH pixels to each cell's fg slot, and
+; wBGP0/wBGP1 steer EMPTY pixels to each cell's bg slot. Clobbers A, DE, HL;
+; preserves B, C (so it runs inside the tilemap column loop).
+; -----------------------------------------------------------------------------
+color_setup:
+    ld a, d
+    ld [wCSL], a
+    ld a, e
+    ld [wCSR], a
+    ; set = union of the (non-black) colors of both cells
+    xor a
+    ld [wCSset], a
+    ld a, [wCSL]
+    and $0F
+    call cs_add                 ; fg left
+    ld a, [wCSL]
+    swap a
+    and $0F
+    call cs_add                 ; bg left
+    ld a, [wCSR]
+    and $0F
+    call cs_add                 ; fg right
+    ld a, [wCSR]
+    swap a
+    and $0F
+    call cs_add                 ; bg right
+    ; palette = BestPal[set]
+    ld a, [wCSset]
+    ld l, a
+    ld h, 0
+    ld de, BestPal
+    add hl, de
+    ld a, [hl]
+    ld [wPalAttr], a
+    add a
+    add a
+    add a                       ; palette*8 = SlotOf base
+    ld [wCSpb], a
+    ; foreground masks from the two fg slots (left in high nibble, right in low)
+    ld a, [wCSL]
+    and $0F
+    call cs_slot
+    ld d, a
+    ld a, [wCSR]
+    and $0F
+    call cs_slot
+    ld e, a
+    call cs_planes
+    ld a, [wCStmp0]
+    ld [wFGP0], a
+    ld a, [wCStmp1]
+    ld [wFGP1], a
+    ; background masks from the two bg slots
+    ld a, [wCSL]
+    swap a
+    and $0F
+    call cs_slot
+    ld d, a
+    ld a, [wCSR]
+    swap a
+    and $0F
+    call cs_slot
+    ld e, a
+    call cs_planes
+    ld a, [wCStmp0]
+    ld [wBGP0], a
+    ld a, [wCStmp1]
+    ld [wBGP1], a
+    ret
+
+; cs_add - A = color (0..7); OR its set-bit into wCSset (black contributes none)
+cs_add:
+    or a
+    ret z
+    ld l, a
+    ld h, 0
+    ld de, BitTab
+    add hl, de
+    ld a, [hl]
+    ld hl, wCSset
+    or [hl]
+    ld [hl], a
+    ret
+
+; cs_slot - A = color (0..7) -> A = its id (0..3) in the chosen palette.
+; Addresses with A/HL only so it preserves DE (the caller holds the left id in D
+; across the second call). SlotOf index = wCSpb + color <= 63, so no page carry
+; issue beyond the single adc below.
+cs_slot:
+    ld l, a
+    ld a, [wCSpb]
+    add l
+    add LOW(SlotOf)
+    ld l, a
+    ld a, 0
+    adc HIGH(SlotOf)
+    ld h, a
+    ld a, [hl]
+    ret
+
+; cs_planes - D = id for the high (left) nibble, E = id for the low (right)
+; nibble -> wCStmp0 = plane-0 mask, wCStmp1 = plane-1 mask. An id's bit0 lights
+; plane 0, bit1 lights plane 1; the left cell owns $F0, the right owns $0F.
+cs_planes:
+    xor a
+    bit 0, d
+    jr z, .p0r
+    or $F0
+.p0r
+    bit 0, e
+    jr z, .p0done
+    or $0F
+.p0done
+    ld [wCStmp0], a
+    xor a
+    bit 1, d
+    jr z, .p1r
+    or $F0
+.p1r
+    bit 1, e
+    jr z, .p1done
+    or $0F
+.p1done
+    ld [wCStmp1], a
+    ret
+
+; -----------------------------------------------------------------------------
 ; build_tile - build tile for tile-position DE (E=index, D=bank) from chars
 ; B (left) and C (right). ORs wCurMask into the last pixel row (cursor).
 ; -----------------------------------------------------------------------------
@@ -291,21 +464,39 @@ build_tile::
     ld d, a
     ld a, [de]
     and $0F
-    or c                        ; A = combined pixel row
-    ld e, a                     ; save (DE reloaded next iter)
+    or c                        ; A = glyph row g (left=hi nibble, right=lo)
+    ld c, a                     ; C = g
+    cpl
+    ld d, a                     ; D = ~g (the empty pixels = background)
+    ; plane1 = (g & wFGP1) | (~g & wBGP1)  -> hold in E for the write below
+    ld a, [wFGP1]
+    and c
+    ld e, a
+    ld a, [wBGP1]
+    and d
+    or e
+    ld e, a                     ; E = plane 1
+    ; plane0 = (g & wFGP0) | (~g & wBGP0)  (+cursor underline on the last row)
+    ld a, [wFGP0]
+    and c
+    ld c, a                     ; C = g & wFGP0
+    ld a, [wBGP0]
+    and d
+    or c                        ; A = plane 0 base
+    ld c, a
     ld a, b
     dec a
     jr nz, .nocur               ; last row (b==1)? add cursor underline
     ld a, [wCurMask]
-    or e
+    or c
     jr .wr
 .nocur
-    ld a, e
+    ld a, c
 .wr
     pop hl
     ld [hl+], a                 ; plane 0
-    xor a
-    ld [hl+], a                 ; plane 1 = 0
+    ld a, e
+    ld [hl+], a                 ; plane 1
     ; advance glyph pointers - MUST NOT touch HL (it holds the VRAM dest!)
     ld a, [wGlyphL]
     inc a
@@ -349,7 +540,16 @@ render_tile:
     ld a, [hl+]
     ld [wRT_cL], a
     ld a, [hl]
-    ld [wRT_cR], a
+    ld [wRT_cR], a              ; HL = &cellR
+    ; per-glyph color: read colL/colR from the parallel color buffer, then pick
+    ; the tile's palette + bitplane masks (D=colL, E=colR) via the Fano table.
+    ld de, COL_OFF
+    add hl, de                  ; HL = &colR
+    ld a, [hl-]
+    ld e, a                     ; E = colR
+    ld a, [hl]
+    ld d, a                     ; D = colL
+    call color_setup
     ; cursor mask
     xor a
     ld [wCurMask], a
@@ -418,7 +618,102 @@ render_cursor_tile:
     ld a, [wCurCol]
     srl a                       ; /2 = tile col
     ld c, a
-    jp render_tile
+    call render_tile
+    ; fall through: keep the cursor tile's palette attribute in sync with its
+    ; (possibly just-recolored) cells.
+
+; -----------------------------------------------------------------------------
+; update_cursor_attr - rewrite the tilemap palette attribute for the tile under
+; the cursor, from that tile's two cell colors. The cursor line is always fully
+; on-screen (compute_offset guarantees it), so its physical row = wCurRow minus
+; the view offset with no clamping. Bank bit follows the tile's VRAM position.
+; -----------------------------------------------------------------------------
+update_cursor_attr:
+    ; slot = assign[wCurRow]
+    ld a, [wCurRow]
+    add LOW(wAssign)
+    ld l, a
+    ld a, HIGH(wAssign)
+    adc 0
+    ld h, a
+    ld a, [hl]
+    ld [wTMSlot], a
+    ; color addr = COL_BUF + slot*64 + (wCurCol & $FE)
+    ld l, a
+    ld h, 0
+    add hl, hl
+    add hl, hl
+    add hl, hl
+    add hl, hl
+    add hl, hl
+    add hl, hl                  ; slot*64
+    ld a, [wCurCol]
+    and $FE                     ; left cell of the tile
+    add l
+    ld l, a
+    ld a, h
+    adc 0
+    ld h, a
+    ld de, COL_BUF
+    add hl, de
+    ld a, [hl+]
+    ld d, a                     ; colL
+    ld a, [hl]
+    ld e, a                     ; colR
+    call color_setup            ; -> wPalAttr (masks recomputed, harmless)
+    ; bank bit: pos = slot*20 + (wCurCol/2)
+    ld a, [wTMSlot]
+    ld l, a
+    ld h, 0
+    add hl, hl
+    add hl, hl                  ; *4
+    ld d, h
+    ld e, l
+    add hl, hl
+    add hl, hl                  ; *16
+    add hl, de                  ; *20
+    ld a, [wCurCol]
+    srl a
+    add l
+    ld l, a
+    ld a, h
+    adc 0
+    ld h, a                     ; HL = pos
+    ld a, [wPalAttr]
+    bit 0, h                    ; pos >= 256 -> VRAM bank 1
+    jr z, .noattr_bank
+    or $08
+.noattr_bank
+    ld c, a                     ; C = attribute byte
+    ; physical row = wCurRow - wViewTop
+    ld a, [wCurRow]
+    ld hl, wViewTop
+    sub [hl]
+    ; tilemap attr addr = $9800 + physical*32 + (wCurCol/2), VRAM bank 1
+    ld l, a
+    ld h, 0
+    add hl, hl
+    add hl, hl
+    add hl, hl
+    add hl, hl
+    add hl, hl                  ; *32
+    ld a, h
+    add $98
+    ld h, a
+    ld a, [wCurCol]
+    srl a
+    add l
+    ld l, a
+    ld a, h
+    adc 0
+    ld h, a
+    ld a, 1
+    ld [rVBK], a
+    ld a, c
+    ld [hl], a
+    xor a
+    ld [rVBK], a
+    ret
 
 ; -----------------------------------------------------------------------------
 ; term_redraw - rebuild every tile from the buffer (init / full refresh).
@@ -479,6 +774,24 @@ term_scroll::
     ld [hl+], a
     dec b
     jr nz, .clr
+    ; reset the freed line's colors to the default (1 = white)
+    ld a, [wScratch]
+    ld l, a
+    ld h, 0
+    add hl, hl
+    add hl, hl
+    add hl, hl
+    add hl, hl
+    add hl, hl
+    add hl, hl                  ; *64
+    ld de, COL_BUF
+    add hl, de
+    ld b, TCOLS
+.clrcol
+    ld a, 7
+    ld [hl+], a
+    dec b
+    jr nz, .clrcol
     ; rebuild logical row 17
     ld c, 0
 .build
@@ -549,6 +862,18 @@ term_putc::
     ld [rSVBK], a
     ret
 term_putc_body:
+    ld e, a                     ; save the incoming byte
+    ld a, [wAnsiState]
+    or a
+    jp nz, .ansi_active
+    ld a, e
+    cp 27                       ; ESC begins an ANSI sequence
+    jr nz, .not_esc
+    ld a, 1
+    ld [wAnsiState], a
+    ret
+.not_esc:
+    ld a, e
     cp 10
     jr z, .newline
     cp 13
@@ -569,6 +894,13 @@ term_putc_body:
     ld h, a
     ld a, [wRT_cL]
     ld [hl], a
+    ; record this cell's color in the parallel color buffer
+    push hl
+    ld de, COL_OFF
+    add hl, de
+    ld a, [wCurColor]
+    ld [hl], a
+    pop hl
     ; redraw current cell WITHOUT cursor (shows the char)
     xor a
     ld [wCursorOn], a
@@ -636,6 +968,141 @@ term_putc_body:
     call render_cursor_tile
     ret
 
+; --- ANSI CSI parser (reached when wAnsiState != 0) --------------------------
+.ansi_active:
+    dec a                       ; state 1 (just saw ESC)?
+    jr nz, .ansi_csi            ; else state 2 (inside CSI)
+    ld a, e
+    cp 91                       ; '[' : ESC '[' opens a CSI; anything else aborts
+    jr nz, .ansi_off
+    ld a, 2
+    ld [wAnsiState], a
+    xor a
+    ld [wAnsiParam], a
+    ret
+.ansi_off:
+    xor a
+    ld [wAnsiState], a
+    ret
+.ansi_csi:
+    ld a, e
+    cp 48                       ; '0'
+    jr c, .csi_final
+    cp 58                       ; '9'+1
+    jr nc, .csi_final
+    sub 48                      ; '0' : accumulate decimal parameter
+    ld d, a
+    ld a, [wAnsiParam]
+    add a, a                    ; *2
+    ld c, a
+    add a, a
+    add a, a                    ; *8
+    add c                       ; *10
+    add d
+    ld [wAnsiParam], a
+    ret
+.csi_final:
+    ld a, e
+    cp 109                      ; 'm' : set graphics rendition
+    jr z, .csi_sgr
+    cp 59                       ; ';' : parameter separator
+    jr z, .csi_sep
+    xor a                       ; unknown final byte: end the sequence
+    ld [wAnsiState], a
+    ret
+.csi_sep:
+    call apply_sgr
+    xor a
+    ld [wAnsiParam], a
+    ret
+.csi_sgr:
+    call apply_sgr
+    xor a
+    ld [wAnsiState], a
+    ret
+
+; -----------------------------------------------------------------------------
+; apply_sgr - act on the accumulated SGR parameter in wAnsiParam, updating the
+; packed current color (bg<<4)|fg. Foreground 30..37 / 90..97 map through
+; SgrColorMap (black-fg -> white so it stays visible on black); background
+; 40..47 / 100..107 map straight (0=black..7=white, black bg = our default).
+; 0 = reset both; 39 = default fg; 49 = default bg. Others are ignored.
+; -----------------------------------------------------------------------------
+apply_sgr:
+    ld a, [wAnsiParam]
+    or a
+    jr z, .reset                ; 0 = reset fg+bg
+    cp 30
+    jr c, .done
+    cp 38
+    jr c, .fg                   ; 30..37
+    cp 39
+    jr z, .fgdef                ; 39 = default fg
+    cp 40
+    jr c, .done                 ; 38 (256-color intro): ignore
+    cp 48
+    jr c, .bg                   ; 40..47
+    cp 49
+    jr z, .bgdef                ; 49 = default bg
+    cp 90
+    jr c, .done                 ; 48, 50..89: ignore
+    cp 98
+    jr c, .fgb                  ; 90..97
+    cp 100
+    jr c, .done
+    cp 108
+    jr c, .bgb                  ; 100..107
+.done:
+    ret
+.fg:
+    sub 30
+    jr .setfg
+.fgb:
+    sub 90
+.setfg:
+    ld e, a
+    ld d, 0
+    ld hl, SgrColorMap
+    add hl, de
+    ld a, [hl]                  ; A = fg color 1..7
+    ld e, a
+    ld a, [wCurColor]
+    and $F0
+    or e
+    ld [wCurColor], a
+    ret
+.fgdef:
+    ld a, [wCurColor]
+    and $F0
+    or 7
+    ld [wCurColor], a
+    ret
+.bg:
+    sub 40
+    jr .setbg
+.bgb:
+    sub 100
+.setbg:
+    swap a                      ; bg color 0..7 -> high nibble
+    ld e, a
+    ld a, [wCurColor]
+    and $0F
+    or e
+    ld [wCurColor], a
+    ret
+.bgdef:
+    ld a, [wCurColor]
+    and $0F                     ; bg -> 0 (black/default)
+    ld [wCurColor], a
+    ret
+.reset:
+    ld a, 7                     ; fg=7 (white), bg=0 (black)
+    ld [wCurColor], a
+    ret
+SgrColorMap:
+    ;   blk red grn yel blu mag cyn wht   (ANSI 30..37 -> our 1..7; black->white)
+    db  7,  1,  2,  3,  4,  5,  6,  7
+
 ; -----------------------------------------------------------------------------
 ; term_puts - HL = NUL-terminated string: print via term_putc.
 ; -----------------------------------------------------------------------------