4 files changed, 84 insertions, 1 deletions

diff --git a/usr.bin/oemu/cpu.c b/usr.bin/oemu/cpu.c
index 5689953..07ddc7b 100644
--- a/usr.bin/oemu/cpu.c
+++ b/usr.bin/oemu/cpu.c
@@ -198,6 +198,33 @@ cpu_div(struct oemu_cpu *cpu, inst_t *inst)
 }
 
 /*
+ * Decode the INST_DIV instruction
+ */
+static void
+cpu_br(struct oemu_cpu *cpu, inst_t *inst)
+{
+    struct cpu_regs *regs = &cpu->regs;
+    imm_t imm;
+    addr_t br_to;
+
+    if (inst->rd > NELEM(regs->xreg)) {
+        printf("bad register operand for 'br'\n");
+        return;
+    }
+
+    /*
+     * If we are branching to the reset vector, might
+     * as well reset all state.
+     */
+    br_to = regs->xreg[inst->rd];
+    if (br_to == 0) {
+        cpu_reset(cpu);
+    }
+
+    regs->ip = br_to;
+}
+
+/*
  * Reset a CPU to a default state
  */
 void
@@ -205,11 +232,46 @@ cpu_reset(struct oemu_cpu *cpu)
 {
     struct cpu_regs *regs;
 
+    /*
+     * When an OSMX64 processor first starts up, it will
+     * initially be executing in supervisor mode with all
+     * of its registeres initialized to zeros.
+     */
     regs = &cpu->regs;
     regs->ip = 0;
+    regs->sr_state = CPU_SRS_SV;
+    regs->blr = 0x0;
+    regs->ilr = 0x0;
     memset(regs->xreg, 0x0, sizeof(regs->xreg));
 }
 
+void
+cpu_regdump(struct oemu_cpu *cpu)
+{
+    struct cpu_regs *regs;
+
+    regs = &cpu->regs;
+    printf(
+        "X0=%p, X1=%p, X2=%p\n"
+        "X3=%p, X4=%p, X5=%p\n"
+        "X6=%p, X7=%p, X8=%p\n"
+        "X9=%p, X10=%p, X11=%p\n"
+        "X12=%p, X13=%p, X14=%p\n"
+        "X15=%p, IP=%p,  SRS=%p\n"
+        "BLR=%p, ILR=%p\n",
+        regs->xreg[0], regs->xreg[1],
+        regs->xreg[2], regs->xreg[3],
+        regs->xreg[4], regs->xreg[5],
+        regs->xreg[6], regs->xreg[7],
+        regs->xreg[8], regs->xreg[9],
+        regs->xreg[10], regs->xreg[11],
+        regs->xreg[12], regs->xreg[13],
+        regs->xreg[14], regs->xreg[15],
+        regs->ip, regs->sr_state,
+        regs->blr, regs->ilr
+    );
+}
+
 /*
  * Main instruction execution loop.
  */
@@ -245,6 +307,9 @@ cpu_kick(struct oemu_cpu *cpu, struct sysmem *mem)
         case INST_DIV:
             cpu_div(cpu, inst);
             break;
+        case INST_BR:
+            cpu_br(cpu, inst);
+            break;
         }
 
         /* Is this a halt instruction? */
@@ -259,4 +324,6 @@ cpu_kick(struct oemu_cpu *cpu, struct sysmem *mem)
 
         regs->ip += sizeof(*inst);
     }
+
+    cpu_regdump(cpu);
 }
diff --git a/usr.bin/oemu/include/oemu/cpu.h b/usr.bin/oemu/include/oemu/cpu.h
index df4cc80..882fe93 100644
--- a/usr.bin/oemu/include/oemu/cpu.h
+++ b/usr.bin/oemu/include/oemu/cpu.h
@@ -31,6 +31,7 @@
 #define _OEMU_CPU_H_
 
 #include <sys/types.h>
+#include <sys/param.h>
 #include <stdint.h>
 #include <stddef.h>
 #include <oemu/types.h>
@@ -38,6 +39,12 @@
 #define MEMORY_SIZE 512
 
 /*
+ * Processor state register
+ */
+#define CPU_SRS_SV      BIT(1)  /* Supervisor flag */
+#define CPU_SRS_CARRY   BIT(2)  /* Carry flag */
+
+/*
  * System memory
  *
  * @mem: Data
@@ -53,16 +60,23 @@ struct sysmem {
  *
  * @xreg: X<n>
  * @ip: Instruction pointer
+ * @sr_state: Processor state register
+ * @blr: Branch link register
+ * @ilr: Interrupt link register
  */
 struct cpu_regs {
     reg_t xreg[16];
     reg_t ip;
+    reg_t sr_state;
+    reg_t blr;
+    reg_t ilr;
 };
 
 struct oemu_cpu {
     struct cpu_regs regs;
 };
 
+void cpu_regdump(struct oemu_cpu *cpu);
 void cpu_reset(struct oemu_cpu *cpu);
 void cpu_kick(struct oemu_cpu *cpu, struct sysmem *mem);
 
diff --git a/usr.bin/oemu/include/oemu/osmx64.h b/usr.bin/oemu/include/oemu/osmx64.h
index e9baae0..b1df5d3 100644
--- a/usr.bin/oemu/include/oemu/osmx64.h
+++ b/usr.bin/oemu/include/oemu/osmx64.h
@@ -48,6 +48,7 @@
 #define INST_SRL      0x12    /* Shift right logical operation */
 #define INST_MOV_IMM  0x13    /* Data move operation from IMM */
 #define INST_HLT      0x14    /* Halt */
+#define INST_BR       0x15    /* Branch */
 
 /* Registers */
 #define REG_X0   0x00
diff --git a/usr.bin/oemu/include/oemu/types.h b/usr.bin/oemu/include/oemu/types.h
index 0769c84..caf6e9b 100644
--- a/usr.bin/oemu/include/oemu/types.h
+++ b/usr.bin/oemu/include/oemu/types.h
@@ -33,7 +33,8 @@
 #include <sys/types.h>
 
 typedef uint64_t reg_t;
-typedef uintptr_t paddr_t;
+typedef uintptr_t addr_t;
 typedef uint16_t imm_t;
+typedef addr_t paddr_t;
 
 #endif  /* !_OEMU_TYPES_H_ */