libc: add Sprinter palette API (graphics + text planes)
palette.h/video/palette.c wrap BIOS $A4 PIC_SET_PAL/PIC_GET_PAL and $A6 SET_PAL_INIT for the 8 palette pages (0-3 graphics, 4-7 text planes). gfx_palette.c and conio/text_palette.c are thin per-domain wrappers; text_palette.c maps the text "plane" 0..3 (paper/ink/blink-paper/ blink-ink) onto BIOS pages 4..7. Covered by tests/text_palette. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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/*
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* text_palette.c — text-mode palette wrappers.
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*
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* Thin layer over libc/video/palette.c. Translates the text "plane
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* number" 0..3 (paper/ink/blink-paper/blink-ink) into the underlying
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* BIOS palette page 4..7 used by $A4.
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*
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* For an introduction to the four-plane text colour model see
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* <palette.h> (top-of-file doc-block).
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*/
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#include <stdint.h>
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#include <conio.h>
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#include <palette.h>
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void text_pal_load(uint8_t plane, uint8_t start, uint8_t count,
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const uint8_t *data)
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{
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pal_load((uint8_t)(plane + 4u), start, count, data);
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}
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void text_pal_set_color(uint8_t plane, uint8_t attr,
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uint8_t r, uint8_t g, uint8_t b)
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{
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pal_set_color((uint8_t)(plane + 4u), attr, r, g, b);
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}
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void text_pal_get(uint8_t plane, uint8_t start, uint8_t count, uint8_t *data)
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{
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pal_get((uint8_t)(plane + 4u), start, count, data);
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}
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void text_pal_get_color(uint8_t plane, uint8_t attr,
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uint8_t *r, uint8_t *g, uint8_t *b)
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{
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pal_get_color((uint8_t)(plane + 4u), attr, r, g, b);
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}
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void text_pal_reset(void)
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{
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pal_reset(PAL_CGA);
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}
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@@ -0,0 +1,74 @@
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/*
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* gfx_palette.c — graphics-side palette wrappers.
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*
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* The "legacy" entry points (gfx_pal_load / gfx_pal_set) keep their own
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* inline-asm implementation rather than thunking through pal_*; this
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* avoids depending on SDCC's __sdcccall(1) stack-shuffling for nested
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* calls, which empirically misbehaves here (the trampoline corrupts the
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* text palette so the next text-mode print hangs). Functionally these
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* are identical to the old gfx_core.c versions.
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*
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* The newer get / reset helpers are simple wrappers — they're either
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* not on hot paths or are first introduced here, so the thunk overhead
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* doesn't matter and we get to share the asm with libc/video/palette.c.
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*/
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#include <stdint.h>
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#include <gfx.h>
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#include <palette.h>
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static uint8_t gpl_num_;
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static uint8_t gpl_start_;
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static uint8_t gpl_count_;
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static uint16_t gpl_data_;
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void gfx_pal_load(uint8_t pal_num, uint8_t start, uint8_t count,
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const uint8_t *data)
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{
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gpl_num_ = pal_num;
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gpl_start_ = start;
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gpl_count_ = count;
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gpl_data_ = (uint16_t)(uintptr_t)data;
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__asm
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push ix
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ld a, (_gpl_start_)
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ld e, a ; E = start
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ld a, (_gpl_count_)
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ld d, a ; D = count (0 → 256)
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ld hl, (_gpl_data_) ; HL = data
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ld b, #0xFF ; mask
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ld a, (_gpl_num_) ; A = palette number
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ld c, #0xA4 ; BIOS PIC_SET_PAL
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rst #0x08
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pop ix
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__endasm;
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}
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void gfx_pal_set(uint8_t pal_num, uint8_t idx,
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uint8_t r, uint8_t g, uint8_t b)
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{
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uint8_t entry[4];
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entry[0] = b;
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entry[1] = g;
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entry[2] = r;
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entry[3] = 0;
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gfx_pal_load(pal_num, idx, 1, entry);
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}
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void gfx_pal_get(uint8_t pal_num, uint8_t start, uint8_t count,
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uint8_t *data)
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{
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pal_get(pal_num, start, count, data);
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}
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void gfx_pal_get_color(uint8_t pal_num, uint8_t idx,
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uint8_t *r, uint8_t *g, uint8_t *b)
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{
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pal_get_color(pal_num, idx, r, g, b);
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}
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void gfx_pal_reset(void)
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{
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pal_reset(PAL_GRAPH);
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}
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@@ -0,0 +1,89 @@
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/*
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* palette.h — Sprinter palette (low-level).
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*
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* The Sprinter has eight 256-colour palette pages, shared by graphics and
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* text modes:
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*
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* pal_num 0..3 — graphics palettes. Each character cell selects which
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* of the four it uses through bits 7..6 of its mode byte.
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* Used by graphics modes 0x81 / 0x82.
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* pal_num 4..7 — text-mode planes — together they form the colour table
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* of the text-mode attribute byte:
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* 4 = paper (background, non-blink phase)
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* 5 = ink (foreground, non-blink phase)
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* 6 = paper-blink (background during blink half-cycle)
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* 7 = ink-blink (foreground during blink half-cycle)
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* Each plane holds 256 BGR colours indexed directly by
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* the 8-bit attribute byte of the cell.
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*
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* Entry format — 4 bytes per colour, in Blue-Green-Red-pad order; the pad
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* byte is reserved and must be 0.
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*
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* Notes on the underlying BIOS ($A4):
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* - `count = 0` means 256 entries (full plane).
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* - On write, data is AND-masked against `pal_mask` before reaching
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* VRAM. pal_load/pal_set_color hard-code mask = 0xFF (no masking).
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*
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* Blink semantics (text planes):
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* The hardware constantly alternates between planes 4↔6 (paper) and
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* 5↔7 (ink). To DISABLE blink everywhere in IBM-CGA style, copy plane
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* 4 → 6 and 5 → 7 (so both phases show the same colour). To ENABLE
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* ZX-Spectrum style flash, swap entries 6 ↔ 7 for the desired attrs.
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* The system default (PAL_CGA) leaves flash visible only for attribute
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* bytes with bit 7 set.
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*
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* Backed by BIOS PIC_SET_PAL/PIC_GET_PAL ($A4) and SET_PAL_INIT ($A6).
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* Higher-level wrappers live in <conio.h> (text_pal_*) and <gfx.h>
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* (gfx_pal_*); use those directly unless you need raw plane control.
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*/
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#ifndef PALETTE_H
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#define PALETTE_H
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#include <stdint.h>
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/* Default-palette types for pal_reset(). Values match BIOS $A6 B-register. */
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#define PAL_GRAPH 1 /* graphics palette (planes 0..3) */
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#define PAL_SINCLAIR 2 /* Spectrum palette (text planes 4..7, ZX colours) */
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#define PAL_CGA 3 /* CGA text palette (text planes 4..7, IBM CGA) */
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/* Load a contiguous block of palette entries.
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* pal_num: 0..7 (0..3 graphics, 4..7 text)
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* start: first slot (0..255)
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* count: number of slots (0 means 256)
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* bgr0: pointer to count entries of 4 bytes each: Blue, Green, Red, 0 */
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void pal_load(uint8_t pal_num, uint8_t start, uint8_t count,
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const uint8_t *bgr0);
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/* Read a contiguous block of palette entries back into RAM.
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* Same parameter shape as pal_load — bgr0 here is a write buffer of
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* count*4 bytes that receives B,G,R,0 quadruples. */
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void pal_get (uint8_t pal_num, uint8_t start, uint8_t count,
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uint8_t *bgr0);
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/* Convenience: set one entry from an RGB triple. */
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void pal_set_color(uint8_t pal_num, uint8_t slot,
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uint8_t r, uint8_t g, uint8_t b);
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/* Convenience: read one entry into R,G,B pointers (any may be NULL). */
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void pal_get_color(uint8_t pal_num, uint8_t slot,
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uint8_t *r, uint8_t *g, uint8_t *b);
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/* Restore a built-in default palette (BIOS $A6 SET_PAL_INIT).
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* type: PAL_GRAPH / PAL_SINCLAIR / PAL_CGA.
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* Internally:
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* PAL_GRAPH → A=0, E=0, B=1 (resets graphics palette 0)
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* PAL_SINCLAIR → A=0, E=0, B=2
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* PAL_CGA → A=0, E=0, B=3 (resets all text planes 4..7)
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*
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* Use pal_reset_at() if you need a non-zero page or a non-zero graphics
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* palette index. */
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void pal_reset(uint8_t type);
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/* Full-control variant of pal_reset.
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* pal_page: BIOS A register — "palette page" hardware index.
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* graph_pal: BIOS E register — for PAL_GRAPH, target palette 0..3.
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* type: BIOS B register — PAL_GRAPH / PAL_SINCLAIR / PAL_CGA. */
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void pal_reset_at(uint8_t type, uint8_t pal_page, uint8_t graph_pal);
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#endif
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@@ -0,0 +1,131 @@
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/*
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* palette.c — Sprinter palette (BIOS $A4 PIC_SET_PAL / PIC_GET_PAL,
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* BIOS $A6 SET_PAL_INIT).
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*
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* Direction in $A4 is selected by bit 7 of A:
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* A = pal_num → write entries from RAM to VRAM
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* A = 0x80 | pal_num → read entries from VRAM into RAM
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*
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* Lives under libc/video/ because palette control is shared between
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* graphics (mode 0x81/0x82) and text (mode 0x03) — pal_num 0..3 for
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* graphics, 4..7 for the four text-mode planes. The conio and gfx
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* subsystems each ship thin domain-specific wrappers on top.
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*/
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#include <stdint.h>
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#include <palette.h>
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/* Statics used to pass parameters to the inline asm — SDCC __sdcccall(1)
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* gives us only HL natively, so the rest go through memory. */
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static uint8_t pal_num_;
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static uint8_t pal_start_;
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static uint8_t pal_count_;
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static uint16_t pal_data_;
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/* ---- $A4 PIC_SET_PAL — write entries to VRAM --------------------- */
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void pal_load(uint8_t pal_num, uint8_t start, uint8_t count,
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const uint8_t *bgr0)
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{
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pal_num_ = pal_num;
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pal_start_ = start;
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pal_count_ = count;
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pal_data_ = (uint16_t)(uintptr_t)bgr0;
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__asm
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push ix
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ld a, (_pal_start_)
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ld e, a ; E = start
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ld a, (_pal_count_)
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ld d, a ; D = count (0 → 256)
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ld hl, (_pal_data_) ; HL = data
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ld b, #0xFF ; B = mask (no AND)
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ld a, (_pal_num_) ; A = palette number (bit7 = 0 → write)
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ld c, #0xA4 ; BIOS PIC_SET_PAL
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rst #0x08
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pop ix
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__endasm;
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}
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/* ---- $A4 PIC_GET_PAL — read entries from VRAM -------------------- *
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* Same function id; bit 7 of A flips it to read mode. */
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void pal_get(uint8_t pal_num, uint8_t start, uint8_t count, uint8_t *bgr0)
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{
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pal_num_ = (uint8_t)(pal_num | 0x80); /* bit 7 = read */
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pal_start_ = start;
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pal_count_ = count;
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pal_data_ = (uint16_t)(uintptr_t)bgr0;
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__asm
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push ix
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ld a, (_pal_start_)
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ld e, a ; E = start
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ld a, (_pal_count_)
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ld d, a ; D = count (0 → 256)
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ld hl, (_pal_data_) ; HL = buffer
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ld b, #0xFF ; B = mask
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ld a, (_pal_num_) ; A = 0x80 | pal_num → read
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ld c, #0xA4 ; BIOS PIC_GET_PAL (= $A4)
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rst #0x08
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pop ix
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__endasm;
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}
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/* ---- one-colour helpers ------------------------------------------ */
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void pal_set_color(uint8_t pal_num, uint8_t slot,
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uint8_t r, uint8_t g, uint8_t b)
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{
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uint8_t entry[4];
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entry[0] = b;
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entry[1] = g;
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entry[2] = r;
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entry[3] = 0;
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pal_load(pal_num, slot, 1, entry);
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}
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void pal_get_color(uint8_t pal_num, uint8_t slot,
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uint8_t *r, uint8_t *g, uint8_t *b)
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{
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uint8_t entry[4];
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pal_get(pal_num, slot, 1, entry);
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if (b) *b = entry[0];
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if (g) *g = entry[1];
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if (r) *r = entry[2];
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}
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/* ---- $A6 SET_PAL_INIT — restore a built-in default palette ------- *
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* Signature: A = pal_page, E = graphics palette index (0..3), B = type.
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* Type is one of PAL_GRAPH (1) / PAL_SINCLAIR (2) / PAL_CGA (3). */
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static uint8_t reset_page_;
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static uint8_t reset_graph_;
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static uint8_t reset_type_;
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void pal_reset_at(uint8_t type, uint8_t pal_page, uint8_t graph_pal)
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{
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reset_type_ = type;
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reset_page_ = pal_page;
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reset_graph_ = graph_pal;
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__asm
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push ix
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ld a, (_reset_graph_)
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ld e, a ; E = graphics palette index (0..3)
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ld a, (_reset_type_)
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ld b, a ; B = type (1=GRAPH, 2=SINCLAIR, 3=CGA)
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ld a, (_reset_page_) ; A = palette page (last — A is needed)
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ld c, #0xA6 ; BIOS SET_PAL_INIT
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rst #0x08
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pop ix
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__endasm;
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}
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void pal_reset(uint8_t type)
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{
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pal_reset_at(type, 4, 0);
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pal_reset_at(type, 5, 0);
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pal_reset_at(type, 6, 0);
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pal_reset_at(type, 7, 0);
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}
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