working text mode

CMakeLists.txt

@@ -26,7 +26,7 @@ pico_generate_pio_header(${PROJECT_NAME}
         ${CMAKE_CURRENT_LIST_DIR}/video_dma.pio
 )
 
-target_sources(picopal PRIVATE main.c cvideo.c)
+target_sources(picopal PRIVATE main.c cvideo.c text_mode.c)
 
 
 pico_set_program_name(picopal "picopal")

cvideo.h

@@ -10,6 +10,12 @@
 #define WORDS_PER_LINE   (VIDEO_WIDTH / 32)
 #define LINES_PER_FIELD  (VIDEO_HEIGHT / 2)
 
+// Active and visible field in the framebuffer
+#define START_X 35
+#define END_X (VIDEO_WIDTH-40)
+#define START_Y 20
+#define END_Y (VIDEO_HEIGHT-40)
+
 typedef uint32_t video_framebuffer_t[VIDEO_HEIGHT][WORDS_PER_LINE];
 typedef uint32_t (*video_framebuffer_ptr_t)[WORDS_PER_LINE];
 

main.c

@@ -5,112 +5,67 @@
 #include "pico/multicore.h"
 
 #include "cvideo.h"
+#include "text_mode.h"
 
-#include "font.xbm"
 
-static video_framebuffer_t fb0, fb1;
-
-#define START_X 35
-#define END_X (VIDEO_WIDTH-40)
-#define START_Y 20
-#define END_Y (VIDEO_HEIGHT-40)
-
-#define CHARS_PER_LINE 32
-#define CHAR_LINES 20
-
-static char text_mode_buffer[20][32];
-
-static void clear(video_framebuffer_t fb){
-    memset(fb, 0, sizeof(video_framebuffer_t));
-}
-
-static void set_bit(video_framebuffer_t fb, uint x, uint y, bool value) {
-    if(x>=VIDEO_WIDTH || y>=VIDEO_HEIGHT)
-        return;
-    uint index_x = x / 32;
-    uint pos_x = x % 32;
-
-    uint flag = value << (31-pos_x);
-    if(value)
-        fb[y][index_x] |= flag;
-    else
-        fb[y][index_x] &= ~flag;
-}
-
-#define CHAR_WIDTH font_width / 16
-#define CHAR_HEIGHT font_height / 16
-
-void draw_character(video_framebuffer_t fb, unsigned int x, unsigned int y, unsigned int scale, char character) {
-    uint8_t row = character / 16;
-    uint8_t column = character % 16;
-    uint32_t font_x = column * 10;
-    uint32_t font_y = row * 12;
-
-    for (int j = font_y; j < font_y + CHAR_HEIGHT; j++) {
-        for  (int i = font_x; i <  font_x + CHAR_WIDTH; i++) {
-            // XBM images pad rows with zeros
-            uint32_t array_position;
-            if (font_width %8 != 0) {
-                array_position = (j * (font_width + (8 - font_width % 8))) + i;
-            }
-            else {
-                array_position = (j * font_width) + i;
-            }
-            uint32_t array_index = array_position / 8;
-            // XBM image, low bits are first
-            uint32_t byte_position = array_position % 8;
-
-            uint8_t value = font_bits[array_index] >> byte_position & 1 ;
-
-            for (int sx = 0; sx < scale; sx++) {
-                for (int sy = 0; sy < scale; sy++) {
-                    set_bit(fb, x + ((i - font_x) * scale) + sx, y + ((j- font_y) * scale) + sy, !value);
-                }
-            }
-        }
-    }
-}
+// --------------------------------
+// CORE 1
+// --------------------------------
 
 void core1_entry() {
-    gpio_init(25);
-    gpio_set_dir(25, GPIO_OUT);
-    while (true) {
-        gpio_put(25, 1);
-        sleep_ms(500);
-        gpio_put(25, 0);
-        sleep_ms(500);
-    }
+    // Nothing yet
 }
 
+// --------------------------------
+
+
+// --------------------------------
+// CORE 0
+// --------------------------------
+
+static video_framebuffer_t fb0, fb1;
+static text_mode_buffer_t text_mode_buffer;
+
+static bool framebuffer_switched = true;
+static bool text_mode = true;
 
 void framebuffer_switched_cb(){
+    framebuffer_switched = true;
 }
 
 void main() {
     stdio_init_all();
     multicore_launch_core1(core1_entry);
 
-    clear(fb0);
-    clear(fb1);
-    video_init(fb0);
+    init_font_cache();
+
     video_set_framebuffer_switched_cb(framebuffer_switched_cb);
+    video_init(fb0);
+
+    memset(text_mode_buffer, 0, CHAR_LINES*CHARS_PER_LINE);
+    strcpy(&text_mode_buffer[0][0], "PicoPAL text mode");
+    strcpy(&text_mode_buffer[1][0], "-----------------");
+
+    gpio_init(25);
+    gpio_set_dir(25, GPIO_OUT);
 
     int fbnum = 1;
     video_framebuffer_ptr_t fbs[] = {fb0, fb1};
-    int i = 0;
     while (true) {
-        clear(fbs[fbnum]);
-        for(int y=0; y<20; y++){
-            for(int x=0; x<32; x++){
-                draw_character(fbs[fbnum], START_X+x*(CHAR_WIDTH+1)*2, START_Y+y*(CHAR_HEIGHT+1)*2, 2, '0'+(i+x+y)%10);
-            }
-        }
 
-        video_set_framebuffer(fbs[fbnum]);
+        // Check if need to draw new frame
+        if(framebuffer_switched){
+            gpio_put(25, fbnum);
+
+            if(text_mode){
+                draw_text_mode(fbs[fbnum], text_mode_buffer);
+            }
             fbnum = (fbnum+1)%2;
-        i = (i+1)%10;
-        sleep_ms(500);
+            framebuffer_switched = false;
+        }        
 
         tight_loop_contents();
     }
 }
+
+// --------------------------------

text_mode.c

@@ -0,0 +1,131 @@
+#include "text_mode.h"
+
+#include <stdint.h>
+#include <string.h>
+#include "pico/stdlib.h"
+
+#include "font.xbm"
+
+static void clear(video_framebuffer_t fb){
+    memset(fb, 0, sizeof(video_framebuffer_t));
+}
+
+#define CHAR_WIDTH font_width / 16
+#define CHAR_HEIGHT font_height / 16
+
+static uint16_t glyph_rows[256][CHAR_HEIGHT];
+static uint32_t glyph_rows_x2[256][CHAR_HEIGHT];
+
+void init_font_cache() {
+    for (int ch = 0; ch < 256; ++ch) {
+        uint8_t row = ch / 16;
+        uint8_t column = ch % 16;
+        uint32_t font_x = column * CHAR_WIDTH;
+        uint32_t font_y = row * CHAR_HEIGHT;
+
+        for (int j = 0; j < CHAR_HEIGHT; ++j) {
+            uint16_t packed = 0;
+
+            for (int i = 0; i < CHAR_WIDTH; ++i) {
+                uint32_t src_x = font_x + i;
+                uint32_t src_y = font_y + j;
+                uint32_t array_position;
+
+                if ((font_width % 8) != 0) {
+                    array_position = (src_y * (font_width + (8 - font_width % 8))) + src_x;
+                } else {
+                    array_position = (src_y * font_width) + src_x;
+                }
+
+                uint32_t array_index = array_position / 8;
+                uint32_t byte_position = array_position % 8;
+                uint8_t value = (font_bits[array_index] >> byte_position) & 1u;
+
+                if (!value) {
+                    packed |= (uint16_t)(1u << (CHAR_WIDTH - 1 - i));
+                }
+            }
+
+            glyph_rows[ch][j] = packed;
+
+            uint32_t packed_x2 = 0;
+            for (int i = 0; i < CHAR_WIDTH; ++i) {
+                if (packed & (1u << (CHAR_WIDTH - 1 - i))) {
+                    packed_x2 |= (uint32_t)(3u << ((CHAR_WIDTH - 1 - i) * 2));
+                }
+            }
+            glyph_rows_x2[ch][j] = packed_x2;
+        }
+    }
+}
+
+static inline void blit_row_bits(video_framebuffer_t fb, unsigned int x, unsigned int y, uint64_t bits, unsigned int width) {
+    if (y >= VIDEO_HEIGHT || x >= VIDEO_WIDTH || width == 0) {
+        return;
+    }
+
+    if (x + width > VIDEO_WIDTH) {
+        unsigned int old_width = width;
+        width = VIDEO_WIDTH - x;
+        bits >>= (old_width - width);
+    }
+
+    uint word = x >> 5;
+    uint shift = x & 31u;
+    uint64_t aligned = bits << (64u - width - shift);
+    fb[y][word] |= (uint32_t)(aligned >> 32);
+    if (shift + width > 32u && word + 1u < WORDS_PER_LINE) {
+        fb[y][word + 1u] |= (uint32_t)aligned;
+    }
+}
+
+void draw_character(video_framebuffer_t fb, unsigned int x, unsigned int y, unsigned int scale, char character) {
+    if(character==0)
+        return;
+    unsigned char glyph = (unsigned char)character;
+
+    if (scale == 1) {
+        for (int j = 0; j < CHAR_HEIGHT; ++j) {
+            blit_row_bits(fb, x, y + j, glyph_rows[glyph][j], CHAR_WIDTH);
+        }
+        return;
+    }
+
+    if (scale == 2) {
+        for (int j = 0; j < CHAR_HEIGHT; ++j) {
+            uint32_t row_bits = glyph_rows_x2[glyph][j];
+            blit_row_bits(fb, x, y + (j * 2u), row_bits, CHAR_WIDTH * 2u);
+            blit_row_bits(fb, x, y + (j * 2u) + 1u, row_bits, CHAR_WIDTH * 2u);
+        }
+        return;
+    }
+
+    for (int j = 0; j < CHAR_HEIGHT; ++j) {
+        uint16_t row_bits = glyph_rows[glyph][j];
+        for (int sy = 0; sy < (int)scale; ++sy) {
+            for (int i = 0; i < CHAR_WIDTH; ++i) {
+                if (row_bits & (1u << (CHAR_WIDTH - 1 - i))) {
+                    for (int sx = 0; sx < (int)scale; ++sx) {
+                        unsigned int px = x + (unsigned int)(i * scale + sx);
+                        unsigned int py = y + (unsigned int)(j * scale + sy);
+                        if (px < VIDEO_WIDTH && py < VIDEO_HEIGHT) {
+                            uint word = px >> 5;
+                            uint bit = 31u - (px & 31u);
+                            fb[py][word] |= (1u << bit);
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+void draw_text_mode(video_framebuffer_t fb, text_mode_buffer_t buffer){
+    clear(fb);
+    for(int y=0; y<20; y++){
+        for(int x=0; x<32; x++){
+            draw_character(fb, START_X+x*(CHAR_WIDTH+1)*2, START_Y+y*(CHAR_HEIGHT+1)*2, 2, buffer[y][x]);
+        }
+    }
+    video_set_framebuffer(fb);
+}

text_mode.h

@@ -0,0 +1,12 @@
+#pragma once
+
+#include "cvideo.h"
+
+// Text mode config
+#define CHARS_PER_LINE 32
+#define CHAR_LINES 20
+
+typedef char text_mode_buffer_t[CHAR_LINES][CHARS_PER_LINE];
+
+void init_font_cache();
+void draw_text_mode(video_framebuffer_t fb, text_mode_buffer_t buffer);