yay?

4 files changed, 229 insertions, 104 deletions

diff --git a/Makefile b/Makefile
index 10b0a50..e4ea709 100644
--- a/Makefile
+++ b/Makefile
@@ -13,7 +13,8 @@ all: \
 	out/test-find-syms \
 	out/test-find-syms-cpp \
 	out/test-substrate \
-	out/test-dis
+	out/test-dis \
+	out/test-tdarm-simple
 
 out:
 	mkdir out
@@ -22,16 +23,19 @@ out/%.o: lib/%.c Makefile out
 	$(CC) -fvisibility=hidden -std=c11 -c -o $@ $<
 
 LIB_OBJS := out/find-syms.o out/substrate-compat.o
+HEADERS := lib/*.h generated/*.h
 out/libsubstitute.dylib: $(LIB_OBJS) lib/*.h out
 	$(CC) -dynamiclib -fvisibility=hidden -o $@ $(LIB_OBJS)
 
-out/test-dis: test/test-dis.c Makefile
+out/test-tdarm-simple: test/test-tdarm-simple.c $(HEADERS) Makefile
 	$(CC) -std=c11 -o $@ $< -Ilib
-out/test-%: test/test-%.c Makefile out/libsubstitute.dylib
+out/test-dis: test/test-dis.c $(HEADERS) Makefile
+	$(CC) -std=c11 -o $@ $< -Ilib
+out/test-%: test/test-%.c Makefile $(HEADERS) out/libsubstitute.dylib
 	$(CC) -std=c89 -o $@ $< -Ilib -Lout -lsubstitute
-out/test-%-cpp: test/test-%.c Makefile out/libsubstitute.dylib
+out/test-%-cpp: test/test-%.c Makefile $(HEADERS) out/libsubstitute.dylib
 	$(CXX) -x c++ -std=c++98 -o $@ $< -Ilib -Lout -lsubstitute
-out/test-%: test/test-%.cpp Makefile out/libsubstitute.dylib
+out/test-%: test/test-%.cpp Makefile $(HEADERS) out/libsubstitute.dylib
 	$(CXX) -std=c++11 -o $@ $< -Ilib -Isubstrate -Lout -lsubstitute
 
 generated: Makefile
diff --git a/lib/dis-arm.inc.h b/lib/dis-arm.inc.h
index d03025d..fe5c45b 100644
--- a/lib/dis-arm.inc.h
+++ b/lib/dis-arm.inc.h
@@ -1,98 +1,151 @@
+#include "dis.h"
 
-static inline tdis_ret P(GPR_Rt_addr_offset_none_addr_S_21_STL)(tdis_ctx ctx, struct bitslice Rt, struct bitslice addr) {
+#define r(nn)           {.n = nn, .out = false}
+#define rs(nn, l, s)    {.n = bs_slice(nn, l, s), .out = false}
+#define rout(nn)        {.n = nn, .out = true}
+#define rsout(nn, l, s) {.n = bs_slice(nn, l, s), .out = true}
+#define data(...) \
+    struct dis_data_operand ops[] = {__VA_ARGS__}; \
+    return P(data)(ctx, ops, sizeof(ops)/sizeof(*ops));
+
+static tdis_ret P(GPRPairOp_Rt_addr_offset_none_addr_S_2_STLEXD)(tdis_ctx ctx, struct bitslice Rt, struct bitslice addr) {
+    data(r(Rt), r(addr));
 }
-static inline tdis_ret P(GPR_Rn_GPR_Rm_1_ADDrr)(tdis_ctx ctx, struct bitslice Rm, struct bitslice Rn) {
+static tdis_ret P(GPR_Rm_unk_Rd_1_MOVr)(tdis_ctx ctx, struct bitslice Rm, struct bitslice Rd) {
+    data(rout(Rd), r(Rm));
 }
-static inline tdis_ret P(GPR_Rn_3_ADDri)(tdis_ctx ctx, struct bitslice Rn) {
+static tdis_ret P(GPR_Rn_GPR_Rm_unk_Rd_1_ADDrr)(tdis_ctx ctx, struct bitslice Rm, struct bitslice Rd, struct bitslice Rn) {
+    data(rout(Rd), r(Rm), r(Rn));
 }
-static inline tdis_ret P(addr_offset_none_addr_unk_Rt_2_SWP)(tdis_ctx ctx, struct bitslice Rt, struct bitslice addr) {
+static tdis_ret P(GPR_Rn_so_reg_imm_shift_unk_Rd_1_ADDrsi)(tdis_ctx ctx, struct bitslice shift, struct bitslice Rd, struct bitslice Rn) {
+    data(rs(shift, 0, 4), r(Rn), rout(Rd));
 }
-static inline tdis_ret P(GPRPairOp_Rt_addr_offset_none_addr_2_STLEXD)(tdis_ctx ctx, struct bitslice Rt, struct bitslice addr) {
-    return P(reg)(ctx, addr, 0, 4);
+static tdis_ret P(GPR_Rn_so_reg_reg_shift_unk_Rd_1_ADDrsr)(tdis_ctx ctx, struct bitslice shift, struct bitslice Rd, struct bitslice Rn) {
+    data(rs(shift, 0, 4), rs(shift, 8, 4), r(Rn), rout(Rd));
 }
-static inline tdis_ret P(GPR_Rt_addrmode3_addr_S_2_STRD)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {
-    return P(regs3)(ctx, addr, 9, 4, addr, 0, 4, Rt, 0, 4);
+static tdis_ret P(GPR_Rn_unk_Rd_1_ADDri)(tdis_ctx ctx, struct bitslice Rd, struct bitslice Rn) {
+    data(rout(Rd), r(Rn));
 }
-static inline tdis_ret P(GPR_Rt_addrmode3_pre_addr_S_2_STRD_PRE)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {
-    return P(regs3)(ctx, addr, 9, 4, addr, 0, 4, Rt, 0, 4);
+static tdis_ret P(GPR_Rt_4_MCR)(tdis_ctx ctx, struct bitslice Rt) {
+    data(r(Rt));
 }
-static inline tdis_ret P(adrlabel_label_1_ADR)(tdis_ctx ctx, struct bitslice label) {
-    return P(adr)(ctx, ctx->pc + 8 + bs_get(label, ctx->op));
+static tdis_ret P(GPR_Rt_addr_offset_none_addr_S_10_STL)(tdis_ctx ctx, struct bitslice Rt, struct bitslice addr) {
+    data(r(addr), rout(Rt));
 }
-static inline tdis_ret P(br_target_target_B_1_Bcc)(tdis_ctx ctx, struct bitslice target) {
-    return P(branch)(ctx, ctx->pc + 8 + sext(bs_get(target, ctx->op), 24));
+static tdis_ret P(GPR_Rt_addr_offset_none_addr_am2offset_imm_offset_S_4_STRBT_POST_IMM)(tdis_ctx ctx, UNUSED struct bitslice offset, struct bitslice Rt, struct bitslice addr) {
+    data(r(addr), r(Rt));
 }
-static inline tdis_ret P(GPR_Rt_S_1_STRrs)(tdis_ctx ctx, struct bitslice Rt) {
+static tdis_ret P(GPR_Rt_addr_offset_none_addr_am2offset_reg_offset_S_4_STRBT_POST_REG)(tdis_ctx ctx, struct bitslice offset, struct bitslice Rt, struct bitslice addr) {
+    data(r(addr), rs(offset, 0, 4), r(Rt));
 }
-static inline tdis_ret P(GPRnopc_Rt_S_1_STRBrs)(tdis_ctx ctx, struct bitslice Rt) {
+static tdis_ret P(GPR_Rt_addr_offset_none_addr_am3offset_offset_S_2_STRD_POST)(tdis_ctx ctx, struct bitslice offset, struct bitslice Rt, struct bitslice addr) {
+    data(r(addr), rs(offset, 0, 4), r(Rt));
 }
-static inline tdis_ret P(unk_Rt_11_VMOVRRD)(tdis_ctx ctx, struct bitslice Rt) {}
-static inline tdis_ret P(addr_offset_none_addr_8_STC2L_OPTION)(tdis_ctx ctx, struct bitslice addr) {}
-static inline tdis_ret P(GPR_Rt_addrmode_imm12_addr_1_STRi12)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {}
-static inline tdis_ret P(addrmode5_addr_S_8_STC2L_OFFSET)(tdis_ctx ctx, struct bitslice addr) {
-    return P(reg)(ctx, addr, 9, 4);
+static tdis_ret P(GPR_Rt_addr_offset_none_addr_postidx_imm8_offset_S_1_STRHTi)(tdis_ctx ctx, UNUSED struct bitslice offset, struct bitslice Rt, struct bitslice addr) {
+    data(r(addr), r(Rt));
 }
-static inline tdis_ret P(addrmode5_pre_addr_S_4_STC2L_PRE)(tdis_ctx ctx, struct bitslice addr) {
-    return P(reg)(ctx, addr, 9, 4);
+static tdis_ret P(GPR_Rt_addrmode3_addr_S_2_STRD)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {
+    data(rs(addr, 9, 4), rs(addr, 0, 4), r(Rt));
 }
-static inline tdis_ret P(GPRnopc_Rt_addrmode_imm12_addr_1_STRBi12)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {
-    return P(reg)(ctx, addr, 13, 4);
+static tdis_ret P(GPR_Rt_addrmode3_pre_addr_S_2_STRD_PRE)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {
+    data(rs(addr, 9, 4), rs(addr, 0, 4), r(Rt));
 }
-static inline tdis_ret P(GPR_Rt_addrmode_imm12_pre_addr_2_STRB_PRE_IMM)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {
-    return P(reg)(ctx, addr, 13, 4);
+static tdis_ret P(GPR_Rt_addrmode_imm12_addr_S_1_STRi12)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {
+    data(rs(addr, 13, 4), r(Rt));
 }
-static inline tdis_ret P(GPR_Rt_ldst_so_reg_addr_2_STRB_PRE_REG)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {
-    return P(regs2)(ctx, addr, 13, 4, addr, 0, 4);
+static tdis_ret P(GPR_Rt_addrmode_imm12_pre_addr_S_2_STRB_PRE_IMM)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {
+    data(rs(addr, 13, 4), r(Rt));
+}
+static tdis_ret P(GPR_Rt_ldst_so_reg_addr_S_2_STRB_PRE_REG)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {
+    data(rs(addr, 0, 4), rs(addr, 13, 4), r(Rt));
+}
+static tdis_ret P(GPR_Rt_ldst_so_reg_shift_S_1_STRrs)(tdis_ctx ctx, struct bitslice shift, struct bitslice Rt) {
+    data(rs(shift, 0, 4), rs(shift, 13, 4), r(Rt));
+}
+static tdis_ret P(GPRnopc_Rt_4_MCRR)(tdis_ctx ctx, UNUSED struct bitslice Rt) {
+    // need Rt2 but whatever
+    return P(unidentified)(ctx);
+}
+static tdis_ret P(GPRnopc_Rt_addrmode_imm12_addr_S_1_STRBi12)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {
+    data(rs(addr, 13, 4), r(Rt));
+}
+static tdis_ret P(GPRnopc_Rt_ldst_so_reg_shift_S_1_STRBrs)(tdis_ctx ctx, struct bitslice shift, struct bitslice Rt) {
+    data(rs(shift, 13, 4), rs(shift, 0, 4), r(Rt));
+}
+static tdis_ret P(addr_offset_none_addr_4_LDC2L_OPTION)(tdis_ctx ctx, struct bitslice addr) {
+    data(r(addr));
+}
+static tdis_ret P(addr_offset_none_addr_S_4_STC2L_OPTION)(tdis_ctx ctx, struct bitslice addr) {
+    data(r(addr));
+}
+static tdis_ret P(addr_offset_none_addr_am2offset_imm_offset_unk_Rt_4_LDRBT_POST_IMM)(tdis_ctx ctx, UNUSED struct bitslice offset, struct bitslice Rt, struct bitslice addr) {
+    data(r(addr), rout(Rt));
+}
+static tdis_ret P(addr_offset_none_addr_am2offset_reg_offset_unk_Rt_4_LDRBT_POST_REG)(tdis_ctx ctx, struct bitslice offset, struct bitslice Rt, struct bitslice addr) {
+    data(r(addr), rs(offset, 0, 4), rout(Rt));
+}
+static tdis_ret P(addr_offset_none_addr_am3offset_offset_unk_Rt_4_LDRD_POST)(tdis_ctx ctx, struct bitslice offset, struct bitslice Rt, struct bitslice addr) {
+    data(r(addr), rs(offset, 0, 4), rout(Rt));
+}
+static tdis_ret P(addr_offset_none_addr_postidx_imm8_offset_unk_Rt_3_LDRHTi)(tdis_ctx ctx, UNUSED struct bitslice offset, struct bitslice Rt, struct bitslice addr) {
+    data(r(addr), rout(Rt));
+}
+static tdis_ret P(addr_offset_none_addr_postidx_imm8s4_offset_4_LDC2L_POST)(tdis_ctx ctx, UNUSED struct bitslice offset, struct bitslice addr) {
+    data(r(addr));
+}
+static tdis_ret P(addr_offset_none_addr_postidx_imm8s4_offset_S_4_STC2L_POST)(tdis_ctx ctx, UNUSED struct bitslice offset, struct bitslice addr) {
+    data(r(addr));
+}
+static tdis_ret P(addr_offset_none_addr_unk_Rt_16_LDA)(tdis_ctx ctx, struct bitslice Rt, struct bitslice addr) {
+    data(r(addr), rout(Rt));
+}
+static tdis_ret P(addrmode3_addr_unk_Rt_4_LDRD)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {
+    data(rsout(addr, 9, 4), rs(addr, 0, 4), r(Rt));
+}
+static tdis_ret P(addrmode3_pre_addr_unk_Rt_4_LDRD_PRE)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {
+    data(rsout(addr, 9, 4), rs(addr, 0, 4), r(Rt));
+}
+static tdis_ret P(addrmode5_addr_8_LDC2L_OFFSET)(tdis_ctx ctx, struct bitslice addr) {
+    data(rsout(addr, 9, 4));
+}
+static tdis_ret P(addrmode5_addr_S_4_STC2L_OFFSET)(tdis_ctx ctx, struct bitslice addr) {
+    data(rs(addr, 9, 4));
+}
+static tdis_ret P(addrmode5_pre_addr_4_LDC2L_PRE)(tdis_ctx ctx, struct bitslice addr) {
+    data(rs(addr, 9, 4));
+}
+static tdis_ret P(addrmode5_pre_addr_S_4_STC2L_PRE)(tdis_ctx ctx, struct bitslice addr) {
+    data(rs(addr, 9, 4));
+}
+static tdis_ret P(addrmode_imm12_addr_unk_Rt_2_LDRBi12)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {
+    data(rs(addr, 13, 4), rout(Rt));
+}
+static tdis_ret P(addrmode_imm12_pre_addr_unk_Rt_2_LDRB_PRE_IMM)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {
+    data(rs(addr, 13, 4), rout(Rt));
+}
+static tdis_ret P(adrlabel_label_1_ADR)(tdis_ctx ctx, struct bitslice label) {
+    return P(adr)(ctx, ctx->pc + 8 + bs_get(label, ctx->op));
+}
+static tdis_ret P(br_target_target_B_1_Bcc)(tdis_ctx ctx, struct bitslice target) {
+    return P(branch)(ctx, ctx->pc + 8 + sext(bs_get(target, ctx->op), 24));
+}
+static tdis_ret P(ldst_so_reg_addr_unk_Rt_2_LDRB_PRE_REG)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {
+    data(rs(addr, 0, 4), rs(addr, 13, 4), rout(Rt));
+}
+static tdis_ret P(ldst_so_reg_shift_unk_Rt_2_LDRBrs)(tdis_ctx ctx, struct bitslice shift, struct bitslice Rt) {
+    data(rs(shift, 0, 4), rs(shift, 13, 4), rout(Rt));
+}
+static tdis_ret P(tcGPR_Rm_unk_Rd_1_MOVr_TC)(tdis_ctx ctx, struct bitslice Rm, struct bitslice Rd) {
+    data(rout(Rd), r(Rm));
+}
+static tdis_ret P(unk_Rd_5_MOVTi16)(tdis_ctx ctx, struct bitslice Rd) {
+    data(rout(Rd));
+}
+static inline tdis_ret P(unk_Rt_13_MRC)(tdis_ctx ctx, struct bitslice Rt) {
+    data(rout(Rt));
 }
 
-
-static inline tdis_ret P(so_reg_imm_shift_14_ADCrsi)(tdis_ctx ctx, struct bitslice shift) {}
-static inline tdis_ret P(so_reg_reg_shift_14_ADCrsr)(tdis_ctx ctx, struct bitslice shift) {}
-static inline tdis_ret P(addr_offset_none_addr_unk_Rt_31_LDA)(tdis_ctx ctx, struct bitslice Rt, struct bitslice addr) {
-    /* hope nobody's SWPping into PC */
-    return P(reg)(ctx, addr, 0, 4);
-}
-static inline tdis_ret P(GPR_Rt_addr_offset_none_addr_S_21_STL)(tdis_ctx ctx, struct bitslice Rt, struct bitslice addr) {
-    return P(regs)(ctx, addr, 0, 4, addr, 0, 0, &Rt);
-}
-static inline tdis_ret P(adrlabel_label_1_ADR)(tdis_ctx ctx, struct bitslice label) {}
-static inline tdis_ret P(br_target_target_B_1_Bcc)(tdis_ctx ctx, struct bitslice target) {}
-static inline tdis_ret P(GPR_Rt_4_MCR)(tdis_ctx ctx, struct bitslice Rt) {}
-static inline tdis_ret P(GPRnopc_Rt_4_MCRR)(tdis_ctx ctx, struct bitslice Rt) {}
-static inline tdis_ret P(unk_Rt_13_MRC)(tdis_ctx ctx, struct bitslice Rt) {}
-static inline tdis_ret P(addr_offset_none_addr_S_8_STC2L_OPTION)(tdis_ctx ctx, struct bitslice addr) {}
-static inline tdis_ret P(addr_offset_none_addr_8_LDC2L_OPTION)(tdis_ctx ctx, struct bitslice addr) {}
-static inline tdis_ret P(GPR_Rn_GPR_Rm_1_ADDrr)(tdis_ctx ctx, struct bitslice Rm, struct bitslice Rn) {
-    return P(regs2)(ctx, Rm, 0, 4, Rn, 0, 4);
-}
-static inline tdis_ret P(GPR_Rn_so_reg_imm_shift_1_ADDrsi)(tdis_ctx ctx, struct bitslice shift, struct bitslice Rn) {}
-static inline tdis_ret P(GPR_Rn_so_reg_reg_shift_1_ADDrsr)(tdis_ctx ctx, struct bitslice shift, struct bitslice Rn) {}
-static inline tdis_ret P(GPR_Rn_1_ADDri)(tdis_ctx ctx, struct bitslice Rn) {
-    return P(reg)(ctx, Rn, 0, 4);
-}
-static inline tdis_ret P(addrmode3_addr_unk_Rt_4_LDRD)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {}
-static inline tdis_ret P(GPR_Rt_addrmode3_addr_S_2_STRD)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {}
-static inline tdis_ret P(GPR_Rt_addrmode_imm12_addr_S_1_STRi12)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {}
-static inline tdis_ret P(GPR_Rt_ldst_so_reg_shift_S_1_STRrs)(tdis_ctx ctx, struct bitslice shift, struct bitslice Rt) {}
-static inline tdis_ret P(addrmode5_addr_8_LDC2L_OFFSET)(tdis_ctx ctx, struct bitslice addr) {}
-static inline tdis_ret P(addrmode3_pre_addr_unk_Rt_4_LDRD_PRE)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {}
-static inline tdis_ret P(GPR_Rt_addrmode3_pre_addr_S_2_STRD_PRE)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {}
-static inline tdis_ret P(GPRnopc_Rt_addrmode_imm12_addr_S_1_STRBi12)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {}
-static inline tdis_ret P(GPRnopc_Rt_ldst_so_reg_shift_S_1_STRBrs)(tdis_ctx ctx, struct bitslice shift, struct bitslice Rt) {}
-static inline tdis_ret P(addrmode5_addr_S_4_STC2L_OFFSET)(tdis_ctx ctx, struct bitslice addr) {}
-static inline tdis_ret P(addrmode_imm12_addr_unk_Rt_2_LDRBi12)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {}
-static inline tdis_ret P(ldst_so_reg_shift_unk_Rt_2_LDRBrs)(tdis_ctx ctx, struct bitslice shift, struct bitslice Rt) {}
-static inline tdis_ret P(GPR_Rt_addrmode_imm12_pre_addr_S_2_STRB_PRE_IMM)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {}
-static inline tdis_ret P(addrmode5_pre_addr_S_4_STC2L_PRE)(tdis_ctx ctx, struct bitslice addr) {}
-static inline tdis_ret P(GPR_Rt_ldst_so_reg_addr_S_2_STRB_PRE_REG)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {}
-static inline tdis_ret P(addrmode_imm12_pre_addr_unk_Rt_2_LDRB_PRE_IMM)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {}
-static inline tdis_ret P(ldst_so_reg_addr_unk_Rt_2_LDRB_PRE_REG)(tdis_ctx ctx, struct bitslice addr, struct bitslice Rt) {}
-static inline tdis_ret P(addrmode5_pre_addr_4_LDC2L_PRE)(tdis_ctx ctx, struct bitslice addr) {}
-static inline tdis_ret P(GPR_Rm_1_MOVr)(tdis_ctx ctx, struct bitslice Rm) {}
-static inline tdis_ret P(tcGPR_Rm_1_MOVr_TC)(tdis_ctx ctx, struct bitslice Rm) {}
-static inline tdis_ret P(GPRPairOp_Rt_addr_offset_none_addr_S_2_STLEXD)(tdis_ctx ctx, struct bitslice Rt, struct bitslice addr) {}
-
-static inline tdis_ret P(dis_arm)(tdis_ctx ctx) {
+static tdis_ret P(dis_arm)(tdis_ctx ctx) {
     unsigned op = ctx->op;
-    #include "../generated/transform-dis-arm.inc"
+    #include "../generated/transform-dis-arm.inc.h"
 }
diff --git a/lib/dis.h b/lib/dis.h
index 8063235..a45e5d0 100644
--- a/lib/dis.h
+++ b/lib/dis.h
@@ -1,8 +1,7 @@
 #pragma once
+#include <stdbool.h>
 
-static inline int sext(unsigned val, int bits) {
-    return val & (1 << (bits - 1)) ? ((int)val - (1 << bits)) : (int)val;
-}
+#define UNUSED __attribute__((unused))
 
 struct bitslice_run {
     int inpos, outpos, len;
@@ -13,35 +12,52 @@ struct bitslice {
     const struct bitslice_run *runs;
 };
 
-__attribute__((always_inline))
+struct dis_data_operand {
+    struct bitslice n;
+    bool out;
+};
+
+static inline int sext(unsigned val, int bits) {
+    return val & (1 << (bits - 1)) ? ((int)val - (1 << bits)) : (int)val;
+}
+
 static inline unsigned bs_get(struct bitslice bs, unsigned op) {
     unsigned ret = 0;
     for(int i = 0; i < bs.nruns; i++) {
         const struct bitslice_run *run = &bs.runs[i];
-        unsigned masked = op & ((1 << run->len) - 1);
-        if (run->outpos < run->inpos)
-            masked >>= run->inpos - run->outpos;
-        else if (run->outpos > run->inpos)
-            masked <<= run->outpos - run->inpos;
-        ret |= masked;
+        unsigned val = (op >> run->inpos) & ((1 << run->len) - 1);
+        ret |= val << run->outpos;
     }
     return ret;
 }
 
-__attribute__((always_inline))
-static inline unsigned bs_set(struct bitslice bs, unsigned val, unsigned op) {
+static inline unsigned bs_set(struct bitslice bs, unsigned new, unsigned op) {
     for(int i = 0; i < bs.nruns; i++) {
         const struct bitslice_run *run = &bs.runs[i];
         unsigned mask = (1 << run->len) - 1;
-        unsigned masked = val & mask;
-        if (run->outpos < run->inpos) {
-            masked <<= run->inpos - run->outpos;
-            mask <<= run->inpos - run->outpos;
-        } else if (run->outpos > run->inpos) {
-            masked >>= run->outpos - run->inpos;
-            mask >>= run->outpos - run->inpos;
-        }
-        op = (op & ~mask) | masked;
+        unsigned val = (new >> run->outpos) & mask;
+        op = (op & ~(mask << run->inpos)) | (val << run->inpos);
     }
     return op;
 }
+
+static inline struct bitslice bs_slice_(struct bitslice bs, struct bitslice_run *runs, int lo, int size) {
+    int nruns = 0;
+    for(int i = 0; i < bs.nruns; i++) {
+        struct bitslice_run inr = bs.runs[i];
+        inr.outpos -= lo;
+        if(inr.outpos < 0) {
+            inr.len += inr.outpos;
+            inr.inpos -= inr.outpos;
+            inr.outpos = 0;
+        }
+        if(inr.outpos + inr.len > size)
+            inr.len = size - inr.outpos;
+        if(inr.len > 0)
+            runs[nruns++] = (struct bitslice_run) {inr.inpos, inr.outpos, inr.len};
+    }
+    return (struct bitslice) {nruns, runs};
+}
+#define bs_slice(bs, lo, size) \
+    bs_slice_(bs, alloca((bs).nruns * sizeof(struct bitslice_run)), lo, size)
+
diff --git a/test/test-tdarm-simple.c b/test/test-tdarm-simple.c
new file mode 100644
index 0000000..99a5d4a
--- /dev/null
+++ b/test/test-tdarm-simple.c
@@ -0,0 +1,52 @@
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "dis.h"
+
+typedef void tdis_ret;
+typedef struct tc {
+    uint32_t pc;
+    uint32_t op;
+
+} *tdis_ctx;
+#define P(x) P_##x
+
+static void P_data(struct tc *ctx, struct dis_data_operand *ops, size_t nops) {
+    printf("data: %08x\n", ctx->op);
+    for(size_t i = 0; i < nops; i++) {
+        unsigned val = bs_get(ops[i].n, ctx->op);
+        printf("    {");
+        for(int j = 0; j < ops[i].n.nruns; j++) {
+            struct bitslice_run run = ops[i].n.runs[j];
+            printf(" %d:%d:%d", run.inpos, run.outpos, run.len);
+        }
+        printf(" } =>\n");
+        printf("    reg %x: %s\n", val, ops[i].out ? "out" : "in");
+    }
+    unsigned newop = ctx->op;
+    for(size_t i = 0; i < nops; i++)
+        newop = bs_set(ops[i].n, i, newop);
+    printf("modified: %x\n", newop);
+}
+
+static void P_adr(struct tc *ctx, UNUSED uint32_t dpc) {
+    printf("adr: %08x\n", ctx->op);
+}
+
+static void P_branch(struct tc *ctx, UNUSED uint32_t dpc) {
+    printf("branch: %08x\n", ctx->op);
+}
+
+static void P_unidentified(struct tc *ctx) {
+    printf("unidentified: %08x\n", ctx->op);
+
+}
+#include "dis-arm.inc.h"
+
+int main(UNUSED int argc, char **argv) {
+    struct tc ctx;
+    ctx.pc = 0xdead0000;
+    ctx.op = (uint32_t) strtoll(argv[1] ? argv[1] : "deadbeef", NULL, 16);
+    P_dis_arm(&ctx);
+
+}