stuff that doesn't work

README.md

@@ -104,6 +104,15 @@ described near the end, the article is quite large.
 1. ~~The BSL sets up Timer A, while the datasheet only mentions Timer B usage
    in *other* BSLs, and nothing about this one.~~ This is wrong, it changes the
    clock settings, which has an influence on which clock source a timer uses.
+1. The BSL communication method does not depend on the part number (eg. 5994 vs
+   59941), only the values in TLV are checked.
+1. While the code has paths for other UART baudrate settings for the
+   communication interface, only one is available.
+1. The memory area from `0x1b00` to `0x1bff` also contains ROM code, with its
+   own Z-area (also at the beginning, also 8 bytes in size). It has three
+   entrypoints, the fourth is an infinite loop. (`0x3c00..0x3fff` looks like
+   the same type of execute-only memory at first, but actually contains nothing,
+   at least not according to the techniques used here.)
 
 ## What has not been checked
 
@@ -113,6 +122,7 @@ described near the end, the article is quite large.
    [MerryMage's GBA BIOS dump](https://mary.rs/lab/gbabios/))
 1. DMA: can a DMA transfer be used to change the stack contents during BSL
    execution? (Most likely, just like interrupts can, I simply haven't checked.)
+1. Dumping of the `0x1b00`..`0x1bff` region still needs to happen.
 
 ## Hashes
 
@@ -126,6 +136,15 @@ with BSL 00.08.35.B3:
 | SHA-256 | `e4d0d171013f847a357eebe5467bcd413ecb41dc01424b7e4ee636538d820766` |
 | SHA-512 | `fed28a7e9643a551789075b79d9b04fa6e8cdca74d783c1c3830ece07e5c9141dda9532b3c442416a1ddab90d752e679c6918c0d5333ac6da9fd23ab6c33d1bb` |
 
+## Region 2 WIP stuff
+
+* `0x1b00` entrypoint: basically halts the CPU. Not very useful.
+* `0x1b02` jumps to `0x1bc2` which almost immediately disables interrupts.
+* `0x1b04` jumps to `0x1bd6` which almost immediately disables interrupts.
+
+Haven't been able to get around the IRQ disable thing yet... TODO: try NMI? Or
+some timer IRQ sneakiness to get around the IRQ disable code.
+
 ## Proof of concept
 
 The code in `src/main.c` will dump the content of the BSL to `eUSCI_A0` in UART

logtracer.py

@@ -72,7 +72,7 @@ with serial.Serial(sys.argv[1] if len(sys.argv) > 1 else "/dev/ttyACM1", 9600, t
             stack = [int(x,16) for x in stack]
 
             delta = -1
-            if len(recs) > 1:
+            if len(recs) > 0:
                 rec_ = Rec(ticks, delta, pc, sp, sr, gp, stack)
                 for i in range(2, min(15, len(recs))):
                     if recs[-i] == recs[-1]:

src/main.c

@@ -40,6 +40,10 @@ static uint8_t stackbak[16]={0};
 __attribute__((__persistent__))
 static uint16_t curticks = 1;
 
+extern uint16_t done_irq;
+__attribute__((__persistent__, __used__))
+uint16_t done_irq = 0;
+
 
 extern uint16_t curaddr;
 __attribute__((__persistent__))
@@ -56,7 +60,7 @@ typedef void (*bsl_fn)(void);
 #define END_CYC 0xffffu
 
 // DUMP_MODE == 0 => insn trace mode
-#define DUMP_MODE 1
+#define DUMP_MODE 0
 #define DUMP_CYC_OFF 14
 
 void do_trace(void);
@@ -67,10 +71,11 @@ __attribute__((__no_inline__)) void do_trace(void) {
 
 	// init timer TA0
 	__bic_SR_register(GIE);
-#ifdef DUMP_MODE
+#if DUMP_MODE
 	traceaddr = 0x1002;
 	TA1CCR0 = DUMP_CYC_OFF;
 #else
+	done_irq = 0;
 	TA1CCR0 = curticks;
 #endif
 	TA1CCTL0 = CCIE;
@@ -90,7 +95,7 @@ __attribute__((__no_inline__)) void do_trace(void) {
 		"mov.w #0xbeef, r14\n"
 		"mov.w #0xaaaa, r15\n"
 
-#ifdef DUMP_MODE
+#if DUMP_MODE
 		// extra 0x1002 magic
 		"mov.w curaddr, sp\n"
 #endif
@@ -109,6 +114,12 @@ __attribute__((__used__, __no_inline__))
 void do_collect(uint16_t* sp) {
 	TA1CTL &= ~(uint16_t)(TAIE|MC__UP);
 
+	// 0x1bc2/4 and 0x1bd6/8 contain a bic #GIE, sr instruction! these should be 2 bytes in size
+	/*if (pc16 == 0x1bc2 || pc16 == 0x1bc4 || pc16 == 0x1bd6 || pc16 == 0x1bd8) {
+		sp[24] |= 
+	}*/
+	// 0x1b96 does a jump to ???? (probably from a memory location?)
+
 #if DUMP_MODE
 	uint16_t v1 = sp[2*(12-4)];
 	uint16_t v2 = sp[2*(13-4)];
@@ -128,14 +139,16 @@ __attribute__((__used__, __no_inline__))
 	if (curticks < START_SOFT) goto next_iter;
 #endif
 
+	uint16_t sr = sp[24];
+	uint32_t pc = sp[25];
+	//uint16_t pc16 = pc;
+
 	// general purpose registers
 	for (int i = 0; i < 12; ++i) {
 		uint32_t v = sp[(i*2)+0] | ((uint32_t)sp[(i*2)+1] << 16);
 		regbak[i+4] = v;
 	}
 
-	uint16_t sr = sp[24];
-	uint32_t pc = sp[25];
 	pc |= ((uint32_t)(sr & 0xf000) << (16-12));
 	sr &= 0xfff;
 
@@ -178,11 +191,36 @@ __attribute__((__interrupt__(TIMER1_A0_VECTOR), __naked__))
 void Timer_A1_ISR(void) {
 	asm volatile(
 		".extern do_collect\n"
+		".extern done_irq\n"
+		".extern curticks\n"
 
 		//"bis #0x3, P1OUT\n"
 #if DUMP_MODE
+		// get a stack we can do stuff with
+		// (sp is currently in bsl space)
 		"mov.a #(__stack-8), sp\n"
 #endif
+
+/*#if !DUMP_MODE
+		// do some hackery
+		"bit.w #0, done_irq\n"
+		"jnz .Lregular\n"
+
+		// skip pc forward by 4
+		"add.w #4, 2(sp)\n"
+		// set GIE in sr
+		"bis.w #8, 0(sp)\n"
+		// set timer counter for next IRQ for trace
+		"mov.w #1, TA1CCR0\n"
+		// restart timer
+		"bis.w #4, TA1CTL\n"
+		// done it now
+		"mov.w #1, done_irq\n"
+		// continue as usual
+		"reti\n"
+#endif*/
+
+	".Lregular:\n"
 		"pushm.a #12, r15\n"
 		"mov.a sp, r12\n"
 		"call #do_collect\n"
@@ -215,6 +253,7 @@ int main(void) {
 
 	puts("hello world!\r\n");
 
+	done_irq = 0;
 	do_trace();
 	__builtin_unreachable();
 }