1 files changed, 140 insertions, 0 deletions
diff --git a/src/memory.c b/src/memory.c
new file mode 100644
index 0000000..373ca27
--- /dev/null
+++ b/src/memory.c
@@ -0,0 +1,140 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <SDL3/SDL.h>
+#include <sys/mman.h>
+#include "main.h"
+#include "procfs.h"
+#include "hash.h"
+#include "curve.h"
+#include "panic.h"
+#include "memory.h"
+
+uintptr_t to_addr(int x, int y) {
+	unsigned int ux, uy;
+	memcpy(&ux, &x, sizeof(unsigned int));
+	memcpy(&uy, &y, sizeof(unsigned int));
+	uintptr_t page = zorder(ux / PAGE_WIDTH, uy / PAGE_HEIGHT);
+	int offset =
+		x % PAGE_WIDTH / CHAR_BIT + y % PAGE_HEIGHT * PAGE_WIDTH / CHAR_BIT;
+	return page * PAGE_SIZE + offset;
+}
+
+void to_pos(uintptr_t addr, int *x, int *y) {
+	int px, py;
+	unzorder(addr / PAGE_SIZE, &px, &py);
+	int offset = addr % PAGE_SIZE;
+	int ux = px * PAGE_WIDTH + offset % PAGE_WIDTH;
+	int uy = py * PAGE_HEIGHT + offset / PAGE_WIDTH;
+	memcpy(x, &ux, sizeof(int));
+	memcpy(y, &uy, sizeof(int));
+}
+
+int init_page_list(page_list *l, int fd) {
+	l->fd = fd;
+}
+
+static void free_page(page *p) {
+	if (p->tex) {
+		SDL_DestroyTexture(p->tex);
+	}
+	free(p);
+}
+
+void free_page_list(page_list *l) {
+	page *p = l->first;
+	while (p) {
+		page *next = p->next;
+		free_page(p);
+		p = next;
+	}
+	l->fd = -1;
+	l->first = NULL;
+}
+
+void free_unused_pages(page_list *l) {
+	page **prev_link = &l->first;
+	page *p = l->first;
+	while (p) {
+		page *next = p->next;
+		if (!p->in_use) {
+			*prev_link = next;
+			free_page(p);
+		} else {
+			prev_link = &p->next;
+			p->in_use = false;
+		}
+		p = next;
+	}
+}
+
+page *get_page(page_list *l, uintptr_t addr) {
+	addr = addr - addr % PAGE_SIZE;
+	for (page *p = l->first; p; p = p->next) {
+		if (p->address == addr) {
+			return p;
+		}
+	}
+	page *p = calloc(1, sizeof(page));
+	if (!p) panic("out of memory");
+	p->address = addr;
+	p->l = l;
+	p->next = l->first;
+	l->first = p;
+	return p;
+}
+
+static SDL_Palette *texture_palette() {
+	SDL_Color colors[] = {{0x00, 0x00, 0x00, 0xFF}, {0xFF, 0xFF, 0xFF, 0xFF}};
+	static SDL_Palette *palette = NULL;
+	if (!palette) {
+		palette = must(SDL_CreatePalette(2));
+		must(SDL_SetPaletteColors(palette, colors, 0, 2));
+	}
+	return palette;
+}
+
+SDL_Texture *get_texture(page *p) {
+	static char data[PAGE_SIZE];
+	if (read_mem(p->l->fd, p->address, data, PAGE_SIZE) != 0) {
+		return NULL;
+	}
+	uint32_t hash = fnv(data, PAGE_SIZE);
+	if (p->hash != hash) {
+		if (p->tex) SDL_DestroyTexture(p->tex);
+		SDL_Surface *surface = must(SDL_CreateSurfaceFrom(
+			PAGE_WIDTH, PAGE_HEIGHT, SDL_PIXELFORMAT_INDEX1LSB, data,
+			PAGE_WIDTH / 8
+		));
+		p->tex = must(SDL_CreateTextureFromSurface(renderer, surface));
+		must(SDL_SetTexturePalette(p->tex, texture_palette()));
+		SDL_DestroySurface(surface);
+	}
+	p->hash = hash;
+	p->in_use = true;
+	return p->tex;
+}
+
+static void write_bit(int fd, int x, int y, bool bit) {
+	uintptr_t addr = to_addr(x, y);
+	int bit_offs = x % CHAR_BIT;
+	uint8_t byte;
+	if (read_mem(fd, addr, &byte, 1) == -1) return;
+	byte = (byte & ~(1 << bit_offs)) | (bit << bit_offs);
+	write_mem(fd, addr, &byte, 1);
+}
+
+void draw_line(page_list *l,
+		double x1, double y1, double x2, double y2, bool bit) {
+	double dx = (x2 - x1);
+	double dy = (y2 - y1);
+	int step = abs(dx) >= abs(dy) ? abs(dx) : abs(dy);
+	dx = dx / step; dy = dy / step;
+	double x = x1; double y = y1;
+	for (int i = 0; i <= step; i++) {
+		write_bit(l->fd, x, y, bit);
+		x = x + dx;
+		y = y + dy;
+	}
+}