Add PCDRV API, fix warnings and DS region misdetection

2 files changed, 159 insertions, 6 deletions

diff --git a/libpsn00b/include/psxsn.h b/libpsn00b/include/psxsn.h
new file mode 100644
index 0000000..53a3cd9
--- /dev/null
+++ b/libpsn00b/include/psxsn.h
@@ -0,0 +1,54 @@
+/*
+ * PSn00bSDK kernel API library (host file access)
+ * (C) 2023 spicyjpeg - MPL licensed
+ */
+
+/**
+ * @file psxsn.h
+ * @brief Host file access API header
+ *
+ * @details This header provides stubs for the PCDRV API, which grants read and
+ * write access to a directory on the host's filesystem when the executable is
+ * running on an emulator or through a debugger that supports the PCDRV
+ * protocol, such as Unirom or pcsx-redux. These functions are completely
+ * separate and independent from the BIOS file API and do not register any
+ * device drivers.
+ *
+ * Note that in the official SDK these functions are provided by libsn, while
+ * in PSn00bSDK they are part of libpsxapi.
+ */
+
+#ifndef __PSXSN_H
+#define __PSXSN_H
+
+#include <stddef.h>
+
+typedef enum _PCDRV_OpenMode {
+	PCDRV_MODE_READ       = 0,
+	PCDRV_MODE_WRITE      = 1,
+	PCDRV_MODE_READ_WRITE = 2
+} PCDRV_OpenMode;
+
+typedef enum _PCDRV_SeekMode {
+	PCDRV_SEEK_SET = 0,
+	PCDRV_SEEK_CUR = 1,
+	PCDRV_SEEK_END = 2
+} PCDRV_SeekMode;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int PCinit(void);
+int PCcreat(const char *path);
+int PCopen(const char *path, PCDRV_OpenMode mode);
+int PCclose(int fd);
+int PCread(int fd, void *data, size_t length);
+int PCwrite(int fd, const void *data, size_t length);
+int PClseek(int fd, int offset, PCDRV_SeekMode mode);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/libpsn00b/psxapi/_syscalls.s b/libpsn00b/psxapi/_syscalls.s
index 6eaed72..5062b15 100644
--- a/libpsn00b/psxapi/_syscalls.s
+++ b/libpsn00b/psxapi/_syscalls.s
@@ -1,26 +1,28 @@
 # PSn00bSDK syscall wrappers
-# (C) 2022 spicyjpeg - MPL licensed
+# (C) 2022-2023 spicyjpeg - MPL licensed
 
 .set noreorder
 
+## Interrupt enable/disable
+
 .section .text.EnterCriticalSection
 .global EnterCriticalSection
 .type EnterCriticalSection, @function
 EnterCriticalSection:
-	li $a0, 0x01
+	li  $a0, 0x01
 	syscall 0
 
-	jr $ra
+	jr  $ra
 	nop
 
 .section .text.ExitCriticalSection
 .global ExitCriticalSection
 .type ExitCriticalSection, @function
 ExitCriticalSection:
-	li $a0, 0x02
+	li  $a0, 0x02
 	syscall 0
 
-	jr $ra
+	jr  $ra
 	nop
 
 .section .text.SwEnterCriticalSection
@@ -31,7 +33,7 @@ SwEnterCriticalSection:
 	li    $a1, -1026
 	and   $a1, $a0
 	mtc0  $a1, $12
-	andi  $a0, 0x0401 # return ((cop0r12_prev & 0x401) == 0x401)
+	andi  $a0, 0x0401 # return !((cop0r12_prev & 0x401) < 0x401)
 	sltiu $v0, $a0, 0x0401
 
 	jr    $ra
@@ -49,3 +51,100 @@ SwExitCriticalSection:
 
 	jr   $ra
 	nop
+
+## PCDRV (host file access) API
+
+.section .text.PCinit
+.global PCinit
+.type PCinit, @function
+PCinit:
+	break 0, 0x101 # () -> error
+
+	jr    $ra
+	nop
+
+.section .text.PCcreat
+.global PCcreat
+.type PCcreat, @function
+PCcreat:
+	li    $a2, 0
+	move  $a1, $a0
+	break 0, 0x102 # (path, path, 0) -> error, fd
+
+	bgez  $v0, .Lcreate_ok # if (error < 0) fd = error
+	nop
+	move  $v1, $v0
+.Lcreate_ok:
+	jr    $ra # return fd
+	move  $v0, $v1
+
+.section .text.PCopen
+.global PCopen
+.type PCopen, @function
+PCopen:
+	move  $a2, $a1
+	move  $a1, $a0
+	break 0, 0x103 # (path, path, mode) -> error, fd
+
+	bgez  $v0, .Lopen_ok # if (error < 0) fd = error
+	nop
+	move  $v1, $v0
+.Lopen_ok:
+	jr    $ra # return fd
+	move  $v0, $v1
+
+.section .text.PCclose
+.global PCclose
+.type PCclose, @function
+PCclose:
+	move  $a1, $a0
+	break 0, 0x104 # (fd, fd) -> error
+
+	jr    $ra
+	nop
+
+.section .text.PCread
+.global PCread
+.type PCread, @function
+PCread:
+	move  $a3, $a1
+	move  $a1, $a0
+	break 0, 0x105 # (fd, fd, length, data) -> error, length
+
+	bgez  $v0, .Lread_ok # if (error < 0) length = error
+	nop
+	move  $v1, $v0
+.Lread_ok:
+	jr    $ra # return length
+	move  $v0, $v1
+
+.section .text.PCwrite
+.global PCwrite
+.type PCwrite, @function
+PCwrite:
+	move  $a3, $a1
+	move  $a1, $a0
+	break 0, 0x106 # (fd, fd, length, data) -> error, length
+
+	bgez  $v0, .Lwrite_ok # if (error < 0) length = error
+	nop
+	move  $v1, $v0
+.Lwrite_ok:
+	jr    $ra # return length
+	move  $v0, $v1
+
+.section .text.PClseek
+.global PClseek
+.type PClseek, @function
+PClseek:
+	move  $a3, $a2
+	move  $a2, $a1
+	move  $a1, $a0
+	break 0, 0x107 # (fd, fd, offset, mode) -> error, offset
+
+	bgez  $v0, .Lseek_ok # if (error < 0) offset = error
+	nop
+	move  $v1, $v0
+.Lseek_ok:
+	jr    $ra # return offset
+	move  $v0, $v1