Massive rewrite

This commit rewrites the emulator halfway from scratch to make it
easier to change and maintain in the future. The emulator core was
rewritten to adhere to the released Bedrock specification (earlier
versions implemented an older prototype specification, which is no
longer relevant).

This commit also adds proper support for running multiple concurrent
Bedrock instances. This was previously supported in a limited manner
for the on-screen keyboard, but now works for any regular program as
well, with switching being performed by pressing the L or R bumper
buttons. This is disabled by default, as programs will still need to
be baked into the emulator and hand-loaded.

1 files changed, 18 insertions, 43 deletions

diff --git a/arm9/source/bang.c b/arm9/source/bang.c
index 8686dd3..6065267 100644
--- a/arm9/source/bang.c
+++ b/arm9/source/bang.c
@@ -1,51 +1,26 @@
-#include <nds.h>
 #include "bang.h"
 
-static const u8 rev_lookup[] = {
-  0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0,
-  0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0,
-  0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8,
-  0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8,
-  0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4,
-  0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4,
-  0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec,
-  0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc,
-  0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2,
-  0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2,
-  0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea,
-  0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa,
-  0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6,
-  0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6,
-  0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee,
-  0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe,
-  0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1,
-  0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1,
-  0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9,
-  0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9,
-  0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5,
-  0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5,
-  0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed,
-  0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd,
-  0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3,
-  0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3,
-  0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb,
-  0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb,
-  0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7,
-  0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7,
-  0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef,
-  0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff,
-};
 
-u8 rev(u8 x) {
-  return rev_lookup[x];
+// Left-rotate a byte.
+u8 ROL1(u8 v, u8 d) {
+    d %= 8;
+    return v << d | v >> (8-d);
 }
 
-u8 shc(u8 x, u8 y) {
-  y = (u8)(RIGHT(y) - LEFT(y)) % 8;
-  return ((x >> y | (x << (8-y))));
+// Left-rotate a double.
+u16 ROLD(u16 v, u8 d) {
+    d %= 16;
+    return v << d | v >> (16-d);
 }
 
-u16 shcd(u16 x, u8 y) {
-  y = (u16)(RIGHT(y) - LEFT(y)) % 16;
-  return ((x >> y | (x << (16-y))));
+// Right-rotate a byte.
+u8 ROR1(u8 v, u8 d) {
+    d %= 8;
+    return v << (8-d) | v >> d;
+}
+
+// Right-rotate a double.
+u16 RORD(u16 v, u8 d) {
+    d %= 16;
+    return v << (16-d) | v >> d;
 }