[riscv] Create macros for writing characters to the debug console

Abstract out the SBI debug console calls into macros that can be
shared between print_message and print_hex_value.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/arch/riscv/prefix/libprefix.S b/src/arch/riscv/prefix/libprefix.S
index 3cba123acbb3113864bf8a803eea2e0a5c0f9b78..d3278f07debaa3c5f71e515d8b26cd81be22b038 100644 (file)
--- a/src/arch/riscv/prefix/libprefix.S
+++ b/src/arch/riscv/prefix/libprefix.S
@@ -52,6 +52,64 @@ prefix_virt:
        .dword  _prefix
        .size   prefix_virt, . - prefix_virt
 
+/*****************************************************************************
+ *
+ * Print character via debug console extension
+ *
+ *****************************************************************************
+ *
+ * Print a single character via the SBI DBCN extension.
+ *
+ * Parameters:
+ *
+ *   a0 - Character to print
+ *
+ * Returns:
+ *
+ *   a0 - Zero if character printed successfully
+ *   a1 - Overwritten
+ *   a6 - Overwritten
+ *   a7 - Overwritten
+ *
+ */
+
+/* SBI debug console extension */
+#define SBI_DBCN ( ( 'D' << 24 ) | ( 'B' << 16 ) | ( 'C' << 8 ) | 'N' )
+#define SBI_DBCN_WRITE_BYTE 0x02
+
+       .macro  print_char_dbcn
+       li      a7, SBI_DBCN
+       li      a6, SBI_DBCN_WRITE_BYTE
+       ecall
+       .endm
+
+/*****************************************************************************
+ *
+ * Print character via legacy extension
+ *
+ *****************************************************************************
+ *
+ * Print a single character via the SBI putchar legacy extension.
+ *
+ * Parameters:
+ *
+ *   a0 - Character to print
+ *
+ * Returns:
+ *
+ *   a0 - Overwritten
+ *   a7 - Overwritten
+ *
+ */
+
+/* SBI legacy console putchar */
+#define SBI_LEGACY_PUTCHAR 0x01
+
+       .macro  print_char_legacy
+       li      a7, SBI_LEGACY_PUTCHAR
+       ecall
+       .endm
+
 /*****************************************************************************
  *
  * Print message to debug console
@@ -76,13 +134,6 @@ prefix_virt:
  *
  */
 
-/* SBI debug console extension */
-#define SBI_DBCN ( ( 'D' << 24 ) | ( 'B' << 16 ) | ( 'C' << 8 ) | 'N' )
-#define SBI_DBCN_WRITE_BYTE 0x02
-
-/* SBI legacy console putchar */
-#define SBI_LEGACY_PUTCHAR 0x01
-
        .section ".prefix.print_message", "ax", @progbits
        .globl  print_message
 print_message:
@@ -108,13 +159,10 @@ print_message_alt:
        lbu     a0, (t1)
        addi    t1, t1, 1
        beqz    a0, 2f
-       li      a7, SBI_DBCN
-       li      a6, SBI_DBCN_WRITE_BYTE
-       ecall
+       print_char_dbcn
        beqz    a0, 1b
        lbu     a0, -1(t1)
-       li      a7, SBI_LEGACY_PUTCHAR
-       ecall
+       print_char_legacy
        j       1b
 2:
        /* Restore registers and return (via alternate link register) */
@@ -202,14 +250,11 @@ print_hex_value_alt:
 1:     /* Print each digit in turn */
        srli    a0, t1, ( __riscv_xlen - 4 )
        nibble_to_ascii a0
-       li      a7, SBI_DBCN
-       li      a6, SBI_DBCN_WRITE_BYTE
-       ecall
+       print_char_dbcn
        beqz    a0, 2f
        srli    a0, t1, ( __riscv_xlen - 4 )
        nibble_to_ascii a0
-       li      a7, SBI_LEGACY_PUTCHAR
-       ecall
+       print_char_legacy
 2:     slli    t1, t1, 4
        addi    t2, t2, -4
        bgtz    t2, 1b