make pattern sampling safer & more debuggable

memory.c

@@ -4,6 +4,8 @@
 #include <stdbool.h>
 #include <stdlib.h>
 
+static const char JUNK[] = "DUMPSTERDIVEMOTHER666";
+
 // COMMON
 
 void origin_mem_fin(OriginMemSlot *slot) {
@@ -40,6 +42,15 @@ uint16_t origin_mem_size(OriginMemSlot *slot) {
     return 0;
 }
 
+uint8_t origin_mem_read(OriginMemSlot *slot, uint16_t addr) {
+    return slot->read(slot, addr);
+}
+
+void origin_mem_write(OriginMemSlot *slot, uint16_t addr, uint8_t data) {
+    if (slot->write)
+        slot->write(slot, addr, data);
+}
+
 // FIXED
 
 static uint8_t _read_fixed(OriginMemSlot *slot, uint16_t addr) {
@@ -81,7 +92,7 @@ static uint8_t _read_banked(OriginMemSlot *slot, uint16_t addr) {
         if (offset < slot->banked.bank->size)
             return slot->banked.bank->bytes[offset];
     }
-    return 0xFF;
+    return JUNK[addr & sizeof(JUNK)];
 }
 
 static void _write_banked(OriginMemSlot *slot, uint16_t addr, uint8_t data) {
@@ -146,7 +157,7 @@ uint8_t origin_read8(Origin *emu, uint16_t addr) {
     if (slot)
         return slot->read(slot, addr);
     else
-        return 0xFF;
+        return JUNK[addr & sizeof(JUNK)];
 }
 
 void origin_write8(Origin *emu, uint16_t addr, uint8_t data) {
@@ -163,7 +174,7 @@ uint16_t origin_read16(Origin *emu, uint16_t addr) {
     if (slot)
         l = slot->read(slot, addr);
     else
-        l = 0xFF;
+        l = JUNK[addr & sizeof(JUNK)];
 
     ++addr;
     if (!_inrange(addr, slot))
@@ -172,7 +183,7 @@ uint16_t origin_read16(Origin *emu, uint16_t addr) {
     if (slot)
         h = slot->read(slot, addr);
     else
-        h = 0xFF;
+        h = JUNK[addr & sizeof(JUNK)];
 
     return (h << 8) | l;
 }

vg8m.h

@@ -172,6 +172,8 @@ void origin_mem_init_ram(OriginMemSlot *slot, uint16_t addr, uint16_t size);
 void origin_mem_init_rom(OriginMemSlot *slot, uint16_t addr, uint16_t size);
 void origin_mem_init_banked(OriginMemSlot *slot, uint16_t addr, uint16_t size);
 
+uint8_t origin_mem_read(OriginMemSlot *slot, uint16_t addr);
+void origin_mem_write(OriginMemSlot *slot, uint16_t addr, uint8_t data);
 bool origin_mem_set_bank(OriginMemSlot *slot, OriginMemBank *bank);
 
 void origin_bank_init(OriginMemBank *bank, uint16_t size, bool writable);

video.c

@@ -52,39 +52,39 @@ struct sprite {
     uint16_t pat_name;
 };
 
-static inline uint8_t sample_1bpp(uint8_t *pat, uint16_t addr, bool flip_x, bool flip_y, uint8_t x, uint8_t y) {
+static inline uint8_t sample_1bpp(OriginMemSlot *pat, uint16_t addr, bool flip_x, bool flip_y, uint8_t x, uint8_t y) {
     if (!flip_x) x = 7 - x;
     if ( flip_y) y = 7 - y;
 
-    uint8_t b0 = pat[addr + y];
+    uint8_t b0 = origin_mem_read(pat, addr + y);
 
     return b0 >> x & 1;
 }
 
-static inline uint8_t sample_2bpp(uint8_t *pat, uint16_t addr, bool flip_x, bool flip_y, uint8_t x, uint8_t y) {
+static inline uint8_t sample_2bpp(OriginMemSlot *pat, uint16_t addr, bool flip_x, bool flip_y, uint8_t x, uint8_t y) {
     if (!flip_x) x = 7 - x;
     if ( flip_y) y = 7 - y;
 
-    uint8_t b0 = pat[addr + y * 2];
-    uint8_t b1 = pat[addr + y * 2 + 1];
+    uint8_t b0 = origin_mem_read(pat, addr + y * 2);
+    uint8_t b1 = origin_mem_read(pat, addr + y * 2 + 1);
 
     return (b0 >> x & 1) | (b1 << 1 >> x & 2);
 }
 
-static inline uint8_t sample_3bpp(uint8_t *pat, uint16_t addr, bool flip_x, bool flip_y, uint8_t x, uint8_t y) {
+static inline uint8_t sample_3bpp(OriginMemSlot *pat, uint16_t addr, bool flip_x, bool flip_y, uint8_t x, uint8_t y) {
     if (!flip_x) x = 7 - x;
     if ( flip_y) y = 7 - y;
 
-    uint8_t b0 = pat[addr + y * 2];
-    uint8_t b1 = pat[addr + y * 2 + 1];
-    uint8_t b2 = pat[addr + y     + 16];
+    uint8_t b0 = origin_mem_read(pat, addr + y * 2);
+    uint8_t b1 = origin_mem_read(pat, addr + y * 2 + 1);
+    uint8_t b2 = origin_mem_read(pat, addr + y     + 16);
 
     return (b0 >> x & 1) | (b1 << 1 >> x & 2) | (b2 << 2 >> x & 4);
 }
 
 static inline void scan_map(Origin *emu, int y, uint32_t *pixels) {
     OriginRegisters *regs = &emu->hwregs;
-    uint8_t *pat = origin_mem_bytes(&emu->pat_bg);
+    OriginMemSlot *pat = &emu->pat_bg;
 
     if (!pat) return;
 
@@ -112,7 +112,7 @@ static inline void scan_map(Origin *emu, int y, uint32_t *pixels) {
 
 static inline void scan_spr(Origin *emu, int y, uint32_t *pixels) {
     OriginRegisters *regs = &emu->hwregs;
-    uint8_t *pat = origin_mem_bytes(&emu->pat_spr);
+    OriginMemSlot *pat = &emu->pat_spr;
 
     if (!pat) return;
 
@@ -177,7 +177,7 @@ static inline void scan_spr(Origin *emu, int y, uint32_t *pixels) {
 
 void scan_txt(Origin *emu, int y, uint32_t *pixels) {
     OriginRegisters *regs = &emu->hwregs;
-    uint8_t *pat = origin_mem_bytes(&emu->pat_txt);
+    OriginMemSlot *pat = &emu->pat_txt;
 
     if (!pat) return;