diff options
| -rw-r--r-- | README.md | 7 | ||||
| -rw-r--r-- | src/render.c | 60 | ||||
| -rw-r--r-- | src/render.h | 1 |
3 files changed, 59 insertions, 9 deletions
@@ -6,6 +6,13 @@ codes and the Unicode upper-half-block trick (`▀`): each character cell packs two vertical pixels (foreground = top pixel, background = bottom pixel), giving a 160×144 GB screen in 160×72 terminal cells. +To keep terminal load low, output is minimized two ways: SGR color escapes +are only emitted when the fg/bg changes, and **inter-frame diffing** redraws +only the cells that changed since the previous frame (jumping over unchanged +runs with `ESC[row;colH`). A fully static screen writes nothing after the +first frame; on the acid2 screens this cut output from ~7.1 MB to ~65 KB +over 2 s (~108×). Terminal resize (`SIGWINCH`) triggers a full repaint. + ## Build & run ```sh diff --git a/src/render.c b/src/render.c index 72e5558..75ce020 100644 --- a/src/render.c +++ b/src/render.c @@ -5,12 +5,15 @@ #include <unistd.h> #include <termios.h> #include <fcntl.h> +#include <signal.h> #define UPPER "\xe2\x96\x80" // ▀ U+2580 static struct termios orig_termios; static bool raw_active = false; +static void on_winch(int s); + void term_restore(void) { if (raw_active) { tcsetattr(STDIN_FILENO, TCSAFLUSH, &orig_termios); @@ -33,22 +36,50 @@ void term_init(void) { // enter alt screen, hide cursor, clear printf("\x1b[?1049h\x1b[?25l\x1b[2J\x1b[H"); fflush(stdout); + signal(SIGWINCH, on_winch); + render_force_full(); atexit(term_restore); } // large reusable output buffer static char outbuf[SCREEN_W * (SCREEN_H/2) * 40 + 4096]; +// previous frame's pixels, for inter-frame diffing +static u8 prev_fb[SCREEN_H][SCREEN_W][3]; +static bool need_full = true; // force a complete repaint +static volatile sig_atomic_t resized = 0; // set by SIGWINCH + +void render_force_full(void) { need_full = true; } +static void on_winch(int s) { (void)s; resized = 1; } + void render_frame(GB *gb) { PPU *p = &gb->ppu; char *o = outbuf; - o += sprintf(o, "\x1b[H"); + + if (resized) { resized = 0; need_full = true; o += sprintf(o, "\x1b[2J"); } + + // Terminal SGR (color) state persists across cursor moves, so we can keep + // one fg/bg tracker for the whole frame even when we jump over unchanged + // cells. Reset each frame since we emit a final \x1b[0m. + int pr = -1, pg = -1, pb = -1; // last-emitted fg + int PR = -1, PG = -1, PB = -1; // last-emitted bg + int cur_row = -2, cur_col = -2; // terminal cell just written (0-indexed) + for (int y = 0; y < SCREEN_H; y += 2) { - int pr = -1, pg = -1, pb = -1; // prev fg - int PR = -1, PG = -1, PB = -1; // prev bg + int row = y / 2; for (int x = 0; x < SCREEN_W; x++) { u8 *top = p->fb[y][x]; u8 *bot = p->fb[y+1][x]; + if (!need_full) { + u8 *pt = prev_fb[y][x], *pb2 = prev_fb[y+1][x]; + if (top[0]==pt[0] && top[1]==pt[1] && top[2]==pt[2] && + bot[0]==pb2[0] && bot[1]==pb2[1] && bot[2]==pb2[2]) + continue; // cell unchanged -> skip + } + // reposition cursor only when we're not already right after the + // previously written cell + if (row != cur_row || x != cur_col + 1) + o += sprintf(o, "\x1b[%d;%dH", row + 1, x + 1); if (top[0] != pr || top[1] != pg || top[2] != pb) { o += sprintf(o, "\x1b[38;2;%d;%d;%dm", top[0], top[1], top[2]); pr = top[0]; pg = top[1]; pb = top[2]; @@ -58,14 +89,25 @@ void render_frame(GB *gb) { PR = bot[0]; PG = bot[1]; PB = bot[2]; } memcpy(o, UPPER, 3); o += 3; + cur_row = row; cur_col = x; } - memcpy(o, "\x1b[0m\r\n", 6); o += 6; } - o += sprintf(o, "\x1b[0m\x1b[38;2;150;150;150m %.*s " - "[wasd/arrows] z:A x:B space:sel enter:start q:quit\x1b[0m\r\n", - 15, gb->cart.title); - fwrite(outbuf, 1, o - outbuf, stdout); - fflush(stdout); + + // status line: static text, only (re)draw on a full repaint + if (need_full) { + o += sprintf(o, "\x1b[0m\x1b[%d;1H\x1b[38;2;150;150;150m %.*s " + "[wasd/arrows] z:A x:B space:sel enter:start q:quit", + SCREEN_H/2 + 1, 15, gb->cart.title); + } + + memcpy(prev_fb, p->fb, sizeof(prev_fb)); + need_full = false; + + if (o != outbuf) { // nothing changed -> write nothing + o += sprintf(o, "\x1b[0m"); + fwrite(outbuf, 1, o - outbuf, stdout); + fflush(stdout); + } } // ---- input with decay-based "hold" emulation ---- diff --git a/src/render.h b/src/render.h index 15f9cda..93ca32a 100644 --- a/src/render.h +++ b/src/render.h @@ -6,6 +6,7 @@ void term_init(void); void term_restore(void); void render_frame(GB *gb); +void render_force_full(void); // force a complete repaint next frame // Poll keyboard, update gb->buttons. Returns false if quit requested. bool input_poll(GB *gb); |