Created
September 20, 2024 02:21
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| #include <stdint.h> | |
| #include <stdlib.h> | |
| #include <stdbool.h> | |
| extern void busy_loop(void); | |
| extern volatile uint32_t LEDS; | |
| extern volatile struct { | |
| struct { | |
| bool tx_ready : 1; | |
| } control; | |
| uint32_t input; | |
| uint32_t output; | |
| } UART; | |
| void uart_send_c(char c) { | |
| while (!UART.control.tx_ready); | |
| UART.output = c; | |
| } | |
| void uart_send(const char* s) { | |
| for (size_t i = 0; s[i]; i++) { | |
| uart_send_c(s[i]); | |
| } | |
| } | |
| #define FIX_POINT 8 | |
| #define FIX(v) ((fix16)((v) * (1 << FIX_POINT))) | |
| typedef int16_t fix16; | |
| fix16 fix_mul(fix16 a, fix16 b) { | |
| return ((uint32_t)(a) * (uint32_t)(b)) >> FIX_POINT; | |
| } | |
| #define DIV_EXTRA FIX_POINT | |
| fix16 fix_div(fix16 a, fix16 b) { | |
| int32_t r = ((int32_t)(a) << DIV_EXTRA) / (int32_t)(b); | |
| if (FIX_POINT > DIV_EXTRA) { | |
| return r << (FIX_POINT - DIV_EXTRA); | |
| } else { | |
| return r >> (DIV_EXTRA - FIX_POINT); | |
| } | |
| } | |
| fix16 fix_pow(fix16 a, unsigned int b) { | |
| if (b > 1) { | |
| return fix_mul(a, fix_pow(a, b - 1)); | |
| } else if (b == 1) { | |
| return a; | |
| } else { | |
| return FIX(1); | |
| } | |
| } | |
| unsigned int mandel(fix16 x, fix16 y, unsigned int max_iter) { | |
| fix16 zx = x; | |
| fix16 zy = y; | |
| for (unsigned int i = 0; i < max_iter; i++) { | |
| fix16 zxx = fix_mul(zx, zx); | |
| fix16 zyy = fix_mul(zy, zy); | |
| if (zxx + zyy > FIX(4)) { | |
| unsigned int iter = max_iter - i; | |
| return iter > max_iter - 1 ? max_iter - 1 : iter; | |
| } | |
| zy = 2 * fix_mul(zx, zy) + y; | |
| zx = zxx - zyy + x; | |
| } | |
| return 0; | |
| } | |
| const char* COLORMAP_PLAIN[] = { | |
| " ", "@", "#", "%", | |
| "x", "o", ";", ":", | |
| ",", ".", | |
| }; | |
| const char* COLORMAP_ANSI[] = { | |
| " ", | |
| "\033[31;96m@\033[0m", | |
| "\033[31;95m#\033[0m", | |
| "\033[31;94m%\033[0m", | |
| "\033[31;93mx\033[0m", | |
| "\033[31;92mo\033[0m", | |
| "\033[31;91m;\033[0m", | |
| "\033[31;36m:\033[0m", | |
| "\033[31;35m,\033[0m", | |
| "\033[31;34m.\033[0m", | |
| //"\033[31;33m.\033[0m", | |
| //"\033[31;32m.\033[0m", | |
| //"\033[31;31m.\033[0m", | |
| }; | |
| #define COLORMAP COLORMAP_ANSI | |
| void main(void) { | |
| // code assumes width > height | |
| const uint8_t width = 160; | |
| const uint8_t height = 40; | |
| while (true) { | |
| uart_send("\r\nRendering...\r\n\r\n"); | |
| for (uint8_t yi = 0; yi < height; yi++) { | |
| fix16 y = FIX(yi - height / 2); | |
| y = fix_div(y, FIX(height / 2)); | |
| for (uint8_t xi = 0; xi < width; xi++) { | |
| fix16 x = FIX(xi - width / 2); | |
| x = fix_div(x, FIX(height / 2)); | |
| // compensate for aspect ratio somewhat | |
| x = fix_mul(x, FIX(0.5)); | |
| // move the whole thing to the right a bit | |
| x -= FIX(0.7); | |
| unsigned int iters = mandel(x, y, sizeof(COLORMAP) / sizeof(COLORMAP[0])); | |
| uart_send(COLORMAP[iters]); | |
| } | |
| uart_send("\r\n"); | |
| } | |
| for (int i = 0; i < 100; i++) { | |
| busy_loop(); | |
| } | |
| } | |
| } |
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