Add VDP register parsing and dumping.

src/gamegear.c

@@ -206,4 +206,5 @@ const char* gamegear_get_exception(GameGear *gg)
 void gamegear_print_state(const GameGear *gg)
 {
     z80_dump_registers(&gg->cpu);
+    vdp_dump_registers(&gg->vdp);
 }

src/util.h

@@ -10,6 +10,17 @@
 
 #define INVALID_SIZE_CODE 0x8
 
+#define BINARY_FMT "0b%u%u%u%u%u%u%u%u"  // Used by register dumpers
+#define BINARY_VAL(data)       \
+    (data & (1 << 7) ? 1 : 0), \
+    (data & (1 << 6) ? 1 : 0), \
+    (data & (1 << 5) ? 1 : 0), \
+    (data & (1 << 4) ? 1 : 0), \
+    (data & (1 << 3) ? 1 : 0), \
+    (data & (1 << 2) ? 1 : 0), \
+    (data & (1 << 1) ? 1 : 0), \
+    (data & (1 << 0) ? 1 : 0)
+
 /* Functions */
 
 uint8_t bcd_encode(uint8_t);

src/vdp.c

@@ -60,6 +60,38 @@ void vdp_power(VDP *vdp)
 }
 
 /*
+    Return the base address of the pattern name table.
+*/
+static uint16_t get_pnt_base(const VDP *vdp)
+{
+    return (vdp->regs[0x02] & 0x0E) << 10;
+}
+
+/*
+    Return the base address of the sprite attribute table.
+*/
+static uint16_t get_sat_base(const VDP *vdp)
+{
+    return (vdp->regs[0x05] & 0x7E) << 7;
+}
+
+/*
+    Return the base address of the sprite generator table.
+*/
+static uint16_t get_sgt_base(const VDP *vdp)
+{
+    return (vdp->regs[0x06] & 0x04) << 11;
+}
+
+/*
+    Return the CRAM address of the backdrop color.
+*/
+static uint8_t get_backdrop_addr(const VDP *vdp)
+{
+    return ((vdp->regs[0x07] & 0x0F) << 1) + 0x20;
+}
+
+/*
     Advance the V counter for the next scanline.
 */
 static void advance_scanline(VDP *vdp)
@@ -83,6 +115,7 @@ void vdp_simulate_line(VDP *vdp)
     if (vdp->v_counter >= 0x18 && vdp->v_counter < 0xA8) {
         // TODO: draw current line
     }
+    // TODO: if (...) IRQ
     advance_scanline(vdp);
 }
 
@@ -190,3 +223,26 @@ void vdp_write_data(VDP *vdp, uint8_t byte)
     vdp->control_flag = false;
     vdp->read_buf = byte;
 }
+
+/*
+    @DEBUG_LEVEL
+    Print out all register values to stdout.
+*/
+void vdp_dump_registers(const VDP *vdp)
+{
+    const uint8_t *regs = vdp->regs;
+    DEBUG("Dumping VDP register values:")
+
+    DEBUG("- $00:  0x%02X (" BINARY_FMT ")", regs[0x00], BINARY_VAL(regs[0]))
+    DEBUG("- $01:  0x%02X (" BINARY_FMT ")", regs[0x01], BINARY_VAL(regs[1]))
+
+    DEBUG("- $02:  0x%02X (PNT: 0x%04X)", regs[0x02], get_pnt_base(vdp))
+    DEBUG("- $03:  0x%02X (CT)", regs[0x03])
+    DEBUG("- $04:  0x%02X (BPG)", regs[0x04])
+    DEBUG("- $05:  0x%02X (SAT: 0x%04X)", regs[0x05], get_sat_base(vdp))
+    DEBUG("- $06:  0x%02X (SGT: 0x%04X)", regs[0x06], get_sgt_base(vdp))
+    DEBUG("- $07:  0x%02X (BDC: 0x%02X)", regs[0x07], get_backdrop_addr(vdp))
+    DEBUG("- $08:  0x%02X (HS)", regs[0x08])
+    DEBUG("- $09:  0x%02X (VS)", regs[0x09])
+    DEBUG("- $0A:  0x%02X (LC)", regs[0x0A])
+}

src/vdp.h

@@ -41,3 +41,5 @@ uint8_t vdp_read_control(VDP*);
 uint8_t vdp_read_data(VDP*);
 void vdp_write_control(VDP*, uint8_t);
 void vdp_write_data(VDP*, uint8_t);
+
+void vdp_dump_registers(const VDP*);

src/z80.c

@@ -4,6 +4,7 @@
 #include "z80.h"
 #include "disassembler.h"
 #include "logging.h"
+#include "util.h"
 
 #define REG_AF  0
 #define REG_BC  1
@@ -25,17 +26,6 @@
 #define FLAG_ZERO      6
 #define FLAG_SIGN      7
 
-#define BINARY_FMT "0b%u%u%u%u%u%u%u%u"  // Used by z80_dump_registers()
-#define BINARY_VAL(data)       \
-    (data & (1 << 7) ? 1 : 0), \
-    (data & (1 << 6) ? 1 : 0), \
-    (data & (1 << 5) ? 1 : 0), \
-    (data & (1 << 4) ? 1 : 0), \
-    (data & (1 << 3) ? 1 : 0), \
-    (data & (1 << 2) ? 1 : 0), \
-    (data & (1 << 1) ? 1 : 0), \
-    (data & (1 << 0) ? 1 : 0)
-
 /*
     Initialize a Z80 object.