mips: optimize mips_ejtag_step_disable() code

[openocd.git] / src / target / mips_ejtag.c

diff --git a/src/target/mips_ejtag.c b/src/target/mips_ejtag.c
index 9114f8c4cfe799967da7de4d66d3b5ef12b13666..c2bee941d94f4f994322539190cb849b8cbbd2ae 100644 (file)
--- a/src/target/mips_ejtag.c
+++ b/src/target/mips_ejtag.c
@@ -190,49 +190,32 @@ void mips_ejtag_drscan_8_out(struct mips_ejtag *ejtag_info, uint8_t data)
        jtag_add_dr_scan(tap, 1, &field, TAP_IDLE);
 }
 
-static int mips_ejtag_step_enable(struct mips_ejtag *ejtag_info)
+/* Set (to enable) or clear (to disable stepping) the SSt bit (bit 8) in Cp0 Debug reg (reg 23, sel 0) */
+int mips_ejtag_config_step(struct mips_ejtag *ejtag_info, int enable_step)
 {
-       static const uint32_t code[] = {
-                       MIPS32_MTC0(1, 31, 0),                  /* move $1 to COP0 DeSave */
-                       MIPS32_MFC0(1, 23, 0),                  /* move COP0 Debug to $1 */
-                       MIPS32_ORI(1, 1, 0x0100),               /* set SSt bit in debug reg */
-                       MIPS32_MTC0(1, 23, 0),                  /* move $1 to COP0 Debug */
-                       MIPS32_B(NEG16(5)),
-                       MIPS32_MFC0(1, 31, 0),                  /* move COP0 DeSave to $1 */
-       };
+       int code_len = enable_step ? 6 : 7;
 
-       return mips32_pracc_exec(ejtag_info, ARRAY_SIZE(code), code,
-                       0, NULL, 0, NULL, 1);
-}
+       uint32_t *code = malloc(code_len * sizeof(uint32_t));
+       if (code == NULL) {
+               LOG_ERROR("Out of memory");
+               return ERROR_FAIL;
+       }
+       uint32_t *code_p = code;
 
-static int mips_ejtag_step_disable(struct mips_ejtag *ejtag_info)
-{
-       static const uint32_t code[] = {
-                       MIPS32_MTC0(15, 31, 0),                                                 /* move $15 to COP0 DeSave */
-                       MIPS32_LUI(15, UPPER16(MIPS32_PRACC_STACK)),    /* $15 = MIPS32_PRACC_STACK */
-                       MIPS32_ORI(15, 15, LOWER16(MIPS32_PRACC_STACK)),
-                       MIPS32_SW(1, 0, 15),                                                    /* sw $1,($15) */
-                       MIPS32_SW(2, 0, 15),                                                    /* sw $2,($15) */
-                       MIPS32_MFC0(1, 23, 0),                                                  /* move COP0 Debug to $1 */
-                       MIPS32_LUI(2, 0xFFFF),                                                  /* $2 = 0xfffffeff */
-                       MIPS32_ORI(2, 2, 0xFEFF),
-                       MIPS32_AND(1, 1, 2),
-                       MIPS32_MTC0(1, 23, 0),                                                  /* move $1 to COP0 Debug */
-                       MIPS32_LW(2, 0, 15),
-                       MIPS32_LW(1, 0, 15),
-                       MIPS32_B(NEG16(13)),
-                       MIPS32_MFC0(15, 31, 0),                                                 /* move COP0 DeSave to $15 */
-       };
+       *code_p++ = MIPS32_MTC0(1, 31, 0);                      /* move $1 to COP0 DeSave */
+       *code_p++ = MIPS32_MFC0(1, 23, 0),                      /* move COP0 Debug to $1 */
+       *code_p++ = MIPS32_ORI(1, 1, 0x0100);                   /* set SSt bit in debug reg */
+       if (!enable_step)
+               *code_p++ = MIPS32_XORI(1, 1, 0x0100);          /* clear SSt bit in debug reg */
 
-       return mips32_pracc_exec(ejtag_info, ARRAY_SIZE(code), code,
-               0, NULL, 0, NULL, 1);
-}
+       *code_p++ = MIPS32_MTC0(1, 23, 0);                      /* move $1 to COP0 Debug */
+       *code_p++ = MIPS32_B(NEG16((code_len - 1)));            /* jump to start */
+       *code_p = MIPS32_MFC0(1, 31, 0);                        /* move COP0 DeSave to $1 */
 
-int mips_ejtag_config_step(struct mips_ejtag *ejtag_info, int enable_step)
-{
-       if (enable_step)
-               return mips_ejtag_step_enable(ejtag_info);
-       return mips_ejtag_step_disable(ejtag_info);
+       int retval = mips32_pracc_exec(ejtag_info, code_len, code, 0, NULL, 0, NULL, 1);
+
+       free(code);
+       return retval;
 }
 
 int mips_ejtag_enter_debug(struct mips_ejtag *ejtag_info)